Environmental Science Study Outline
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AP Environmental Science Study Outline Kui Tang August 2008
ence: Earth as a Living Planet
This guide follows the College Board's Topic Outline.
Environmental Sci-
by Botkin and Keller, 6th edition, was the main
source for these notes.
Contents 1 Earth Systems and Resources
2
1.1
Earth Science Concepts
. . . . . . . . . . . . . . . . . . . . . . .
1.2
The Atmosphere
3
. . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.3
Global Water Resources and Use
. . . . . . . . . . . . . . . . . .
5
1.4
Soil and Soil Dynamics . . . . . . . . . . . . . . . . . . . . . . . .
7
2 The Living World
8
2.1
Ecosystem Structure . . . . . . . . . . . . . . . . . . . . . . . . .
2.2
Energy Flow
2.3
Ecosystem Diversity
2.4
Natural Ecosystem Change
2.5
Natural Biogeochemical Cycles
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Populations
8 11 11 12 13
14
3.1
Population Biology Concepts
. . . . . . . . . . . . . . . . . . . .
14
3.2
Human Population . . . . . . . . . . . . . . . . . . . . . . . . . .
15
3.2.1
Human Population Dynamics . . . . . . . . . . . . . . . .
15
3.2.2
Population Size . . . . . . . . . . . . . . . . . . . . . . . .
15
3.2.3
Impacts of Population Growth
16
. . . . . . . . . . . . . . .
4 Land and Water Use 4.1
Agriculture
16
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1
Feeding a Growing Population
4.1.2
. . . . . . . . . . . . . . .
16 16
Controlling Pests . . . . . . . . . . . . . . . . . . . . . . .
18
4.2
Forestry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
4.3
Rangelands
4.4
Other Land Uses
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
. . . . . . . . . . . . . . . . . . . . . . . . . . .
19
4.4.1
Urban Land Development . . . . . . . . . . . . . . . . . .
19
4.4.2
Transportation Infrastructure . . . . . . . . . . . . . . . .
21
1
4.4.3
Public and Federal Lands
. . . . . . . . . . . . . . . . . .
22
4.4.4
Land Conservation Options . . . . . . . . . . . . . . . . .
22
4.4.5
Sustainable Land-Use Strategies
22
. . . . . . . . . . . . . .
4.5
Mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
4.6
Fishing
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25
4.7
Global Economics . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
5 Energy Resources and Consumption
26
5.1
Energy Concepts
. . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2
Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . .
27
5.2.1
History
27
5.2.2
Present Global Energy Use
. . . . . . . . . . . . . . . . .
27
5.2.3
Future Energy Needs . . . . . . . . . . . . . . . . . . . . .
28
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3
Fossil Fuel Resources and Use . . . . . . . . . . . . . . . . . . . .
28
5.4
Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.5
Hydroelectric Power
. . . . . . . . . . . . . . . . . . . . . . . . .
32
5.6
Energy Conservation . . . . . . . . . . . . . . . . . . . . . . . . .
33
5.7
Renewable Energy
34
. . . . . . . . . . . . . . . . . . . . . . . . . .
6 Pollution 6.1
6.2
6.3
36
Pollution Types . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
6.1.1
Air Pollution
36
6.1.2
Noise Pollution . . . . . . . . . . . . . . . . . . . . . . . .
41
6.1.3
Water Pollution . . . . . . . . . . . . . . . . . . . . . . . .
42
6.1.4
Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
Impacts on the Environment and Human Health
45
. . . . . . . . .
49
6.2.1
Hazards to Human Health . . . . . . . . . . . . . . . . . .
49
6.2.2
Hazardous Chemicals in the Environment
Economic Impacts
. . . . . . . . .
50
. . . . . . . . . . . . . . . . . . . . . . . . . .
51
7 Global Change
52
7.1
Stratospheric Ozone
. . . . . . . . . . . . . . . . . . . . . . . . .
7.2
Global Warming
52
. . . . . . . . . . . . . . . . . . . . . . . . . . .
54
7.3
Loss of Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . .
57
7.3.1
Habitat loss; overuse; pollution; introduced species; en-
7.3.2
Maintenance Through Conservation
7.3.3
Laws and Treaties
dangered and extinct species
1
26
. . . . . . . . . . . . . . . .
57
. . . . . . . . . . . .
58
. . . . . . . . . . . . . . . . . . . . . .
58
Earth Systems and Resources 1. Average Residence Time (ART): ratio of size of reservoir to rate of transfer through reservoir:
ART = S/F Where
S
is size of reservoir and
F
2
is rate of transfer.
1.1 1.
Earth Science Concepts
Lithosphere is crust.
2. Geological cycles include (a) Tectonic: can create ecological islands. i. Divergent plates boundaries occur at a spreading ocean ridge (sea oor spreading). ii. Convergent plate boundaries occur when plates collide. A.
Subduction
is the heavy ocean rock diving beneath the light
continental rock. May produce coastal mountain ranges (Andes). B. Continental collisions may produce continental mountains. iii. Transform fault boundaries occur when one plate slides past another. (b) Hydrologic (c) Rock (d) Biogeochemical 3.
Earthquake occurs when tectonic plates under pressure rupture, releasing huge amounts of energy (more than a large nuclear explosion), usually at 1015 km along faults. (a) Fault planes bar groundwater. Rocks crushed, then altered into clay. Water forced to surface, creating vital habitats, especially where arid.
4.
Volcanic eruption
occurs when magma rises to the surface.
or
Energy
released varies broadly. Volcanoes occur along tectonic plate boundaries, where active melting of rocks favors extrusion of magma, parts of plates where local hot spots heat and melt rock. 5.
along central
Tsunami is a series of large waves produced after the vertical disturbance of ocean. 80% are produced by earthquakes. They travel at jet aircraft speeds but slow and get taller as they approach the surface.
1.2
The Atmosphere
1. Composition is 78% N2 , 21% O2 , 0.9% Ar, 0.03% CO2 . 2. Structure in order is: troposphere, tropopause (condensation traps water vapor), stratosphere (O3 ), stratopause, mesosphere, mesopause, thermosphere. 3. 25% of incoming solar radiation re ected straight into space, 25% absorbed by atmosphere.
3
4. Atmospheric circulation: (1) rotation and (2) dierential heating.
◦
(a) Low pressure at equator, 5060 .
◦
(b) High pressure from descending air 2530
→
arid. Sandwiched be-
tween two zones of high precipitation (low pressure).
(c) (d)
Easterlies Trade winds
at poles and
Westerlies
from 3060
◦
◦
meet at 60 .
blow to west; meet at equator, where
(regions with little air movement). 5.
doldrums
occur
El Niño events (also ENSO) occur every 27 years, lasting for 11 12 years. East-west trade winds weaken and eastern Paci c waters warm
→ tropical
rainfall shifts from Indonesia to South America. Floods in Peru; droughts
Natural.
and res in Indonesia and Australia. Upwelling at South American coastline is suppressed. (a) 6.
La Niña opposite; exaggerate normal patterns.
Tornadoes are funnel-shaped clouds of rapidly rotating wind.
They form
out of severe thunderstorms that occur when a cold air mass collides with a warm one. Water vapor in the warm part is forced upwards, cools, then precipitates. 7.
Hurricanes are tropical storm with circulating winds of at least 120 km/h that moves across tropical ocean.
tropical depression
(a) An organized mass of thunderstorms with low pressure begin to circulate, forming a
.
(b) Huge amounts of energy are stored as
latent heat
Condensation releases this energy, warming air.
vaporization.
As this air rises,
more water is drawn, increasing the size of the hurricane. (c) Rain bands form as the warm air rises.
warm water increases intensity.
(d) Nearing landfall, hurricanes may slow down in shallower water, but
(e)
Storm surges
occur when the hurricane winds push water towards
the coast, which may rise to be over 10 m and may be exacerbated by high tide. 8.
Heat waves
most deadly
are extended periods of unusually hot weather caused by
heating of atmosphere and moving of air masses. of all weather-related hazards.
They are considered
Global warming may have
increased their severity and incidence.
9.
Droughts are long-term (months to years) periods of usually dry weather that are related to natural cycles of wet and dry years, which in turn are not well understood.
4
10. Coriolis eect is apparent de ection of moving objects when viewed from a rotating frame of reference. (a) Free objects on surface appear to go right in Northern hemisphere and left in southern. (b) Air and water ows
right
in north,
left
in south.
(c) Responsible for cyclones.
1.3 1.
Global Water Resources and Use
Groundwater is water below the water table, which is saturated. (a) Surface water enters at (b) (c)
Vadose zone Aquifer Cone of depression
recharge
and exit at
discharge
20%.
zones.
is unsaturated area above water table where water moves.
is underground zone where water can be extracted at a useful
rate. Gravel or sand. (d) (e)
occurs where well is: water level is locally lower.
E uent streams maintain ow during dry weather by groundwater seepage (they are below water table).
Most perennial streams are
e uent. (f )
In uent
(g)
Reaches
ephemeral stream.
streams are entirely above water table; ows only in re-
sponse to precipitation. Called
are sections of a stream that may be e uent, in uent, or
intermediate. (h) Though reserves are huge (conservatively 200 years of Mississippi ow), pumping costs limit amount that can be economically recovered. i.
Overdraft occurs when withdrawal rate > natural in ow.
ii. Essentially nonrenewable because it can
→
damage ecosystems,
land subsidence. iii. TexasOklahomaHigh Plains area (Ogallala aquifer): prime example. Used 20 times faster than being renewed. 2. Surface and ground-water related: (a) Use groundwater
crease
→
(b) Divert surface water
decrease surface levels
→
decrease ground levels and quality OR
pollutants if divert to recharge zone.
too.
3. Ocean circulation
5
in-
Pollution interrelated
◦
(a) Oceanic conveyor belt:
(Gulf Stream) water 1213 C arrives at
Greenland. Cooled and becomes more saline in North America (2
◦
4 C), sinks to bottom.
Flows south, east, north into Paci c.
Up-
◦
welling starts warm shallow current. Keeps N. Europe 510 C cooler. (b) Forces include: rotation, gravity of moon.
wind
, temperature and salinity dierences,
4. Only 50% of precipitation is considered available 95% of the time. 5.
Desalination will remain expensive because it has place value:
it is very
expensive to transport water.
(a) Discharge of brine waste may damage ecosystems. 6. Stream usage (a) (b) (c)
O-stream use is removal and return (power plant). Consumptive use is not returned (drinking, irrigation). In-stream use uses the stream itself or modi es it. Each use requires dierent rates of discharge that cannot be met simultaneously. i. Hydroelectric power prefers large uctuations. ii. Fish and wildlife prefer larger ows in spring and summer, as does recreation. iii. Navigation prefers constant ow.
(d) Aral Sea demonstrates that removing too much water is deleterious to ecosystems. The sea area has been reduced by 40%, volume by 50%. Economically important sh are dying, and shing towns bordering the sea are now inland. Restoration just beginning. 7. Industrial and domestic use (U.S.) (a) Agriculture, industry began leveling o around 1980. Suggests conservation working. (b) Water for public supply continue to increase. 8. Conservation expects to to increase.
reduce total withdrawals
yet allow consumption
(a) Agriculture can reduce 2030%: i. Don't subsidize water. ii. Integrate surface and groundwater use: use store surface water (in ltration pool or injection well) when abundant, groundwater when not. iii. Use high-tech to maximize delivery e ciency.
Irrigate when
evaporation is minimal. Use improved irrigation (drip).
6
iv. Improve soil:
↑
in ltration,
↓
runo.
v. Use crops that require less water or are more salt-tolerant. (b) Domestic use is only 10%, but
concentrated in urban.
i. Don't do lawns in semi-arid regions! ii. Use e cient bathroom xtures1.6 gpf instead of 5.0. iii. Utilities should price water based on non-linear curve to encourage consumption. (c) Industry can reduce electricity generating water 2530% by using low water/no water evaporation tower, in-plant water reuse. (d)
Perception
impacts people's attitudes toward water conservation.
i. Tucson: people think it's desert; conserve. Water expensive. For example, price per unit increases if usage increases past baseline. ii. Phoenix: water cheap; people don't bother conserving.
need emergency plans to minimize hardship:
9. In wet years, plenty of surface water, and groundwater is recharged. Dry years,
(a) Plan to drill and connect wells for deep groundwater, even though too expensive to normally use. (b) Prepare to treat waste water for reuse when needed.
1.4
Soil and Soil Dynamics
1. Rock Cycle (a) (b)
Igneous rock forms from lava. Cracking, weathering split. Sedimentary rock forms from pressure of lots of sediment: sition + lithi cation.
depo-
i. Weathered rock. ii. Carbon sediments by life. (c)
Metamorphic rock forms from sedimentary rocks transformed through heat, pressure, or chemicals. May be uplifted into open.
2.
Soils
are
earth materials horizons:
modi ed by physical, geological, and biological
processes into
(a) O: black organic layer. Decomposing stu. (b) White powderbleached of organic compounds. (c) A: mineral and organic. Brown/light-black. Minerals leach here. (d) E: lighter-colored because clay, minerals leached. (e) B: zone of accumulation (of leached stu above).
7
(f ) C: parent materialpartially weathered bedrock. 3. Rainwater (pH
= 5.5)
leaches minerals.
4. Soil fertility (a) Young rocks fertile: corn belt (recent glacier). (b) Semiarid regions fertile; need water. (c) Humid areas/tropics infertile: leaching due to rainfall. Most nutrients in vegetation. Succession di cult if forest cleared. 5. Semiarid soils expand and contract with water. Damage buildings. 6.
Clay
hold water.
Sand
allows water to drain. Combination retains water
enough for growth but still drains. Coarser soils more easily eroded.
7. 8.
Loams
are best soils; have all particle sizes.
Landslides
occur when driving forces (gravity) that tend to move soil
and things in the soil down a slope overcome resisting forces that hold the ground in place (interlocking grains, natural cementing, plant roots,
reduces
strength of materials on slope). Addition of water or removal of vegetation resisting forces.
Some landslides are reactivations of prehistoric
slides; these areas repeatedly experience landslides (see La Conchita). (a) In mountains, create lakes by damming valleys. 9.
Floodplain is river and atland draining into it.
Naturally, oods annu-
ally. (a) Deposit nutrients on oodplain. (b) Wetlands provide habitat. (c) Floodplain is distinct from adjacent environments
2
→
diversity.
The Living World
2.1 1.
Ecosystem Structure
Ecosystem is the simplest entity that can sustain life.
Support chemical
cycling and energy ow. 2.
Habitat is where a species lives; niche is what it does. (a) Conservation requires paying attention to both, as well as
symbionts.
obligate
(b) Predation can increase diversity by mitigating competitive exclusion.
8
3.
Watershed de nition of ecosystem:
delineated by land that drains into
same stream. 4.
Community-level interactions occur when a species indirectly
aects
another by aecting intermediary species or the environment. (a) Sea otters (b) 5.
eat key urchins →
allow kelp to grow.
Keystone species are necessary for the basic nature of a community.
Biotic provinces are geographic regions (including ocean) inhabited by characteristic set of taxa sharing
common evolutionary history
and repro-
ductively isolated from other provinces. (a) Formed by continental drift.
(b) Safer to introduce species within its biotic province. 6.
Biomes are de ned by climate, which selects for common traits (convergent evolution).
7.
Island biogeography:
smaller and more distant islands have fewer species.
Migration and evolution supply new species. (a)
Ecological island is a separated small habitat:
park, oceanic island
(over shing), patches of uncut forest. 8. Major biomes
(a) Tundragrasses, mosses, lichens; dwarf shrubs. i. Arctic tundra has large animals; (b) Taiga/Boreal Forestconifers.
alpine tundra
does not.
Low biodiversity; commercially im-
portant. i.
Northern America and Eurasia.
ii. Moose, deer, wolves, bears, foxes, squirrels, rabbits. iii. Water foul, owls, eagles. iv. Disturbances, esp. re, frequent. (c) Temperate Deciduoushardwood trees. i.
China, Japan, W. Europe, U.S., urbanized Canada.
ii. Most changed by humans. iii. Small mammals, birds, insects. (d) Temperate Rain Forestsconifers. i.
North America, New Zealand.
ii. Rare. Conifers because they photosynthesize during non-freezing winter.
9
(e) Temperate Woodlandssmall trees, open. i.
Drier than deciduous forest, same temperature.
ii. Fire regular. iii. Forest plantations in this biome.
chaparral) shrubs.
(f ) Temperate Shrublands ( i.
Mediterranean, SoCal, Chile, S. Africa. Sage
ii. Most attractive to people; little native left. iii.
plant. Aromatic.
iv. Reptiles, small mammals. v. Fire regular. (g) Temperate Grasslandsmidpoint between forest and desert. i.
N. American prairie, steppes of Eurasia, plains of Africa, pampas of South America.
ii. Rich organic soil. iii. Most important agriculturally. iv. Largest abundance and diversity of large mammals. v. Fire and grazing maintain identity as grassland. (h) Tropical Rain Forests i. Soil low in nutrients; plants adapted to rapidly uptake. ii. Found in very remote regions. (i) Tropical Seasonal Forests and Savannas i.
India, Southeast Asia, Africa, South/Central America.
ii. High temperature, variable rainfall. iii. Fire and grazing maintain identity. (j) Desertsrainfall < 50 cm/year. (k) Wetlandssoil has little oxygen; slow decay. Flooded and saturated at least several days a year. i. Bogs have water entry but no outlet. ii. Swamps and marshes have entry and exit. iii. Produce fossil fuels. iv. Bacteria produce CH4 , H2 S. v. Saltwater marsh: breeding ground for oceanic animals. vi. Services: A. Reservoir. Hold high ow; release to augment low ow. B. Important areas of groundwater recharge or discharge. C. 45% endangered animals, 26% endangered birds depends on wetlands. D. Natural lters: plants trap sediment and toxin.
10
E. Important production and storage of biomass, rich soil. vii. Perhaps 90% of freshwater wetlands lost. viii. Urbanization usually on coast, riverbank, or other place favorable to wetlands. ix. Most wetlands now privately owned. (l) Freshwaters i.
Estuaries
mouth of riversrich in nutrients.
ii. Important source of water for animals, civilization. (m) Intertidalmajor economic resource, algae (including kelp). i. Easily polluted; manipulated by people, recreation, urbanization. ii. Extreme changes are part of life. (n) Open Ocean
pelagic region.
Low in N, P.
(o) Benthosdeeps. Food is dead stu that falls from above. Too dark. (p) Upwellingsdeep ocean water rich in nutrients. Flows bring nutrients to surface. West coast of America, Africa, ice caps. Sometimes wind pushes coastal waters away, pulling deep water up. (q) Hydrothermal Ventschemosynthesis. Unusual life-forms. High pressure, extremely variable temperature.
2.2
Energy Flow
1. Photosynthesis and cell respiration 2.
Biological production is capture of energy into organic molecules; net production is the biomass/energy
stored
, not used.
3. Food webs and trophic levels (a) Species that feed on multiple levels classi ed by the highest. (b) Naturally
1% energy transferred between trophic levels.
(c) Many freshwater ecosystems depend on detritus, as benthic. 4. Herbivores can eat stu humans can't eat (algae)
or
graze without damag-
ing land. Vegetarianism for everybody does not maximize food resources.
2.3 1.
Ecosystem Diversity
Biodiversity is expressed as number of species in an area, but popular usage varies. (a) About 1.4M named species, mostly insects and plants and mostly in tropics.
11
(b)
Genetic diversity is total number of genetic characteristics of group (species, subspecies, arbitrary, etc.)
(c) (d)
2.
2.4
Habitat diversity is dierent kinds of habitats in given area. Species diversity i. Species richness is total number, ii. Species evenness is relative abundance, iii. Species dominance is the most abundant species.
Ecosystem services Natural Ecosystem Change
r
1. Ecological Succession: early-succession species are adapted to harsh en-
K
vironment with plentiful resources ( -selected); later species are more resource-e cient but cannot withstand harsh environment (
-selected).
(a) Dune Successionconstantly formed and destroyed along sandy shores. i. Dune grass forms runners underground. Stabilize other seeds. ii. Small, hardy plants grow. iii. Eventually, trees. (b) Bog Successionsedge (grass-like herbs) put oating runners. i. Wind blows stu onto sedge mat; soil forms. ii. Plants grow on sedge; sedge thickens. Really oating mat. iii. Sediments deposit. iv. Eventually, wetland forest. (c) Old-Field Successionsmall, hardy plants, eventually trees. (d) Biodiversity, biomass increase (e) Gross production
↑;
peaks during middle succession.
net production
↓.
(f ) Vegetation retards erosion. (g) Ecosystem eventually runs out of biomass. (h) Species-interaction i. ii.
Facilitationone species prepares way for another (bog). Interferenceearly plants prevent entrance of later (dense grasses prevent other seeds from reaching ground).
iii.
Life history dierenceslowly-propagating
species reaches
succession site later than do quickly-propagating species. iv.
Chronic patchinessenvironment
dominates and succession
never occurs. 2.
Wild res occur when vegetation cannot be decomposed quickly enough to balance the carbon cycle, resulting in an accumulation of fuel.
12
2.5
Natural Biogeochemical Cycles
Chemicals with a gas phase use atmosphere as reservoir and cycle quickly; chemicals lacking gas phase often exist in unusable forms and are often insoluble in water and cycle slowly. 1. Carbon (a) (b) (c) (d)
Reservoirs: Assimilation: Cycling: Loss
atmosphere, ocean, rocks, soil, fossil fuels. photosynthesis.
predation, weathering and erosion.
: respiration, decomposition (release CO2 ), forest res, burning
fossil fuels, volcanic eruption. Fossil fuel formation where too cold or not enough to decompose. (e)
Missing carbon sinkabout 3 GtC (billion metric tons of C) unaccounted for. i. Sink changes size. ii. Believe sink is terrestrial.
(f ) Carbon-silicate cycle: H2 CO3
+ XSiOn + CaCO3 → Ca2+ + HCO− 3 + SiO2
These minerals precipitate and are extracted by marine organisms and form sediment in the ocean. Metamorphosis in subduction zones releases CO2 and reforms silica products. 2. Nitrogen (a) (b) (c)
Reservoirs: Assimilation: Cycling:
air, soil, ocean. nitrogen xation, lightning, industry (50%).
internal, erosion and runo, sea spray. Usually plants rst.
Ruminants have nitrogen- xing bacteria in their stomachs that prove 50% of N. (d)
Loss:
de-nitri cation, marine sedimentation.
3. Phosphorus (a) (b) (c)
Reservoir: Assimilation: Cycling:
phosphates of Ca, K, Mg, Fe. uptake by plants, algae, some bacteria.
to ocean (in soluble form or suspension), ocean-feeding birds
(guano deposits), upwellings (winds push surface water away from land, exposing deeper, nutrient-rich water), uplifting of sedimentary rock. (d)
Loss:
ocean sedimentation.
13
4. Sulfur (a) (b) (c) (d) (e)
Reservoirs Available reservoirs: Assimilation: Cycling: Loss
: rock, soil. air, below ground.
root uptake, gaseous uptake.
litter fall (to ground), root leakage.
: to streams, to atmosphere.
5. Water (a) Local land-use changes can change precipitation. (b)
Drainage basin is land that drains into a particular stream/river.
6. Conservation of matter
3
Populations
3.1
Population Biology Concepts
1. Logistic growth
unrealistic
: relies on
(a) Constant environment (b) Constant
K
(c) Homogeneous population (each has same impact) 2.
K can only be estimated if logistic curve has reached growth rate slows).
in ection point
(when
(a) Estimates before in ection point undershoot. (b)
Maximum sustainable yield 1 2 K , but unrealistic.
20th century.
occurs at
Mis-estimates led to over-harvest in
is the highest rate of growth and
3. Doubling time (reverse of half-life):
Td = where
k
is the constant in
ln 2 0.7 ≈ k k
N = N0 ekt .
14
3.2
Human Population
3.2.1 Human Population Dynamics 1. History (a) Hunter-gatherer; few million. 0.00011%. (b) Agriculture; 0.03% i. A.D. 1: 5M ii. 1600 500M (c) Industrial; 0.1% i. 1800: 900M ii. Doubled twice (3B) by 1960 (d) Modern; 1.2% (Total Fertility Rate = 2.5) 2. 95% of current growth from developing countries. 3. Demographic transition: (a) Lower death rate (medicine against acute illnesses) (b) Then, lower birth rate (education, wealth, social change) (c) Possibly repeat (medicine against chronic illnesses) 4. Age-structure diagrams show past, present, and future.
3.2.2 Population Size 1. Sustainability = zero population growth. 2.
↑
Age of rst childbearing.
(a) 4050% of needed fertility reduction. (b) Sri Lanka. 3. Birth control. (a) Breastfeeding. (b) 46M abortions yearly. 4. National policies: information and access to birth control, explain problems of overpopulation, explain bene ts of fewer children, instituted rewards and punishments. (a) India (1952). (b) Ghana, Malaysia, Pakistan, Singapore, Philippines use tax disincentives.
15
(c) Tanzania restrict maternity leave. (d) Singapore: bigger families more crowded, admission priority for small family. (e) Sri Lanka, Bangladesh, India: government pays you for sterilization. (f ) China i. 1978: goal ZPG by 2000. ii. Achieved 1.0%.
3.2.3 Impacts of Population Growth 1. Ultimate cause of current unsustainability and current environmental problems. 2. Resources and food
per capita peaked in 1960s1970s.
3. Economics (a) Positive feedback in poor countries: low income
→
more children
→
keeps per-capita income low.
4
Land and Water Use
4.1
Agriculture
4.1.1 Feeding a Growing Population 1. Undernourishment: insu cient calories. (a) Marasmuslack of protein and calories. i. Kwashiorkorlack of protein
→
failed neural development.
ii. Chronic hungerunproductive. (b) Malnourishment:
lack of speci c component.
people unproductive.
Long-term.
i. Macronutrients: C, H, N, O, P, S; Ca, Na, K. 2. Types of agriculture (a) (b) (c)
Rangelandfood for grazers/browsers. No plowing. Pastureplanted to provide animal feed. Organic farming i. More like natural ecosystemnot monoculture. ii. Minimize negative impacts. iii. Food does not contain arti cial chemicals.
16
Makes
(d) In
monoculture organic farming
, seed companies predict growing season climates and
likely strains of pests and diseases. If they're wrong, you're screwed. In contrast,
average
plants a mixture of crops or a broad
range of genotypes, resulting in lower risk of very-low-production.
yield but mitigates
Unnatural.
3. Plowing damages soil: succession to dierent climax or much more slowly.
(a) Natural vegetation maintains structure and enriches soil. (b) Plowed land destroys structure and exposes soil; crops remove nutrients; heat decomposes nutrients. (c) Erosion damages water productivity. (d) 1mm soil produced 10 to 40 years. (e) (f ) 4.
Contour plowing is the s0ingle most eective way to reduce erosion. No-till agriculture allow some weeds, leave decaying plants.
Green Revolution is the post-war program that led to crops with higher yields, better disease resistance, or better ability to grow in marginal conditions. (a) Rice hybridization at the International Rice Institute in the Philippines. (b)
Drip irrigation
e cient, but expensive, so not likely used in hungry
places.
5. Genetic engineering and crop production (a) U.S.: 1/3 corn, > 1/2 canola oil, 3/4 soybeans. (b) Hybridization risks: superhybrid can grow where unwanted; superweed had genes transferred to it. (c)
Terminator gene sterilizes seeds.
(d) BT corn produces pesticide in
Prevents GMO spread.
every
cell.
Unknown eect on con-
sumers; toxic pollen can kill monarch butter ies. 6. Key to future food production appears to be increased production per unit area, on increasingly worse land. 7. Global warming
decrease
yield because best soils have best suited climates.
17
4.1.2 Controlling Pests 1.
2 1 3 harvest lost; 10 post-harvest lost. (a) 1050 species of weeds infest each farm.
Devastating: Narrow-spectrum pesticide (b)
2.
cocklebur reduces soybean yield up 60%. targets one organism.
Elusive magic bullet.
(a) Unexpected eects continue to appear. 3. Natural pesticides safe, but not as eective 4.
Biological control uses predators and parasites to control pests. (a)
Bacillus thuringiensis
(BT) infects caterpillars and others.
(b) Parasite wasps (of caterpillars): eective narrow-spectrum. (c) Ladybugs. (d) Sex pheromones to trap or confuse insects. 5.
Integrated pest management uses many techniques to control
rather
than eliminate. (a)
Diminishing returns
as pest removal approaches 100%.
(b) Retaining pest population reduces ecosystem damage.
Physical complexity of habitat reduces pests because it is harder for them to nd food.
(c) Move beyond monoculture.
(d) No/low-till: natural predators of pests accumulate in soil. (e)
4.2
Speci c
application of chemical pesticide.
Forestry
Reduce pressure on other forests.
1. Tree plantations can potentially supply world's timber in 10% of forestland.
2. Forest res (a) Past suppression
→
accumulation of fuel. Now, res are more dam-
aging, and may even burn away organic matter and old trees that normally survive res. 3. Forest management (silviculture) is complex and di cult, but easy to get data (tree rings). (a) Remove poor trees (b) Breed new strains (like crops)
18
(c) Control diseases (usually fungal) and pests.
Little success.
i. Gypsy moth (introduced for silk) defoliate trees. ii. Insects eat leaves, buds, fruits, carry disease. (d) Cutting techniques i.
ii.
Shelterwood-cutting
Always young trees left.
cuts less desirable and dead trees rst.
Seed-tree cutting removes all but a few good, mature ones to promote regeneration.
iii.
Thinning cuts only poor, small trees.
4. National forests compose 11.2% of U.S. area; 12% Costa Rica; depend on amount of forest in country. 5. Clear-cutting is not absolutely bad or good; need to evaluate case-by-case. (a) Level ground, moderate rainfall, clear-cut can regenerate species. 6.
Ecosystem services include retarding erosion, moderating water availability, habitats for endangered species/other wildlife, impacting climate.
4.3 1.
Rangelands
Arid rangeland is easily damaged by grazing; 30% is done there.
2. Cattle trample and erode stream banks and pollute streams. 3.
Overgrazing slows growth, reduces diversity, leads to dominance of un-
desirable plants for grazing. decreases
4. Carrying capacity 5.
with aridity.
Deserti cation is deterioration of dryish land due to climate change and human activity. (a)
Marginal lands
cannot tolerate much human activity. Overstressed.
(b) Poisoned soil (persistent pesticide, . . . ) forces abandonment. (c) Irrigation in arid areas: salt residue accumulates to toxicity.
4.4
Other Land Uses
4.4.1 Urban Land Development 1. 45% live in cities today; 62% by 2025. (a) 75% in developed. (b) 38% is poorer developing.
19
(c) Most estimated to live in country's largest city. 2. Cities, countryside mutually dependent. Many serious environmental problems occur at the interface. 3.
Site is the environmental features of location. (a) Sometimes change: silting harbors destroys economic value.
4.
Situation is placement of city relative to other areas (e.g.
transportation
hub). (a)
Fall line
cities here.
is location of waterfall or rapids on major rivers.
Many
(b) Usually where people would naturally meet: con uence of rivers, river enter lake, next to mineral or spring. 5. Developments that make city seem more independent of nature actually increase dependence. 6. Buildings de ect and channel wind, altering weather patterns. Generally, makes it more di cult to remove pollutants. 7.
Planned development: (a)
Design with nature
fortress city and park city.
attempts to take advantage of features that na-
ture provides instead of destroying nature. (b)
Garden cities are surrounded by greenbelts.
(c) Urban trees face special stress:
soil.
i. Compacted soil. Suer from water extremes.
ii. Air pollution, dust, physical impact
→ ↑
Specially prepare
susceptible to fungal
infection. iii. Must not produce messy leaf, fruit, or owers. iv. Usually, few species used
→
fragile ecosystem.
v. Early succession plants do best. vi. Endangered plants can be planted. Sometimes do well. (d) Habitats for wildlife. Can contribute to conservation. 8. Pests usually are generalists (share people's diet), r-selected. (a) Key to
eliminate habitats.
Don't leave garbage open!
(b) Identify natural t and naturally controlling factors. 9. Adversely aect water cycle.
20
(a) Pavement prevents in ltration. (b) Most cities have one sewer. During storms, runo may exceed treatment capacity, ejecting raw sewage. (c) Evaporation reduced (runo )
→
higher temperature.
(d) Increased particulates
→
(e)
often succeed in controlling runo, recharge
Constructed wetlands
increased rain, clouds, fog.
aquifer, and are cheaper than conventional drainage. 10. Soils lose vegetation 11.
→
lose organic matter, organisms die, compacted.
Urban sprawl is uncontrolled growth, usually of suburbs. (a) Presently, Maryland could urbanize as much land in 25 years as it has in history. (b) Boulder established blue line in 1959no water or sewer beyond. Limited residential and job growth. Economy grew. (c)
However,
neighboring cities grew, and commuting is damaging envi-
ronment. 12.
Made lands are arti cial.
Unnatural.
Unconsolidated
loose ller with-
out rock support. Vulnerable to earthquake.
4.4.2 Transportation Infrastructure 1. Canal have smooth, steep banks, VERY fast water. Drown! (a) Much unforeseen environmental problems: Aswan High Dam + canals
→
snails with schistosomiasis. Nile oodwaters used to ush them.
(b) In some parts, almost everybody is aected by schistosomiasis. 2.
Channelization is modi cation of existing streams (straightening, widening, lining, deepening) to control oods, improve drainage, control erosion, improve navigation. (a) Fast ow lose sh habitats.
Increased temperature, since trees on
banks cut. (b) Downstream ooding worse, since channelized section carries more water than supposed to. (c) Damage wetlands; depresses water table. (d)
Not always bad for environmentdrainage projects bene cial.
3. Roadless areas, when traversed by o-road vehicles, are very sensitive to erosion.
21
4.4.3 Public and Federal Lands 1. Wilderness is area undisturbed by people; the only people are visitors. (a) U.S. Wilderness Act of 1964 de ne wilderness to be preserved. (b)
Limited visitorship and human uses.
(c) Act recognizes ecological value. 2.
Parks are open to public for recreation.
3. Parks/preserves are
ecological islands;
if one is too small, it will be inef-
fective for conservation.
4. Management should involve minimal human activity and: (a) Preserve undisturbed nature of wilderness, (b) Provide people with wilderness experience.
4.4.4 Land Conservation Options 1. Restoration: controversial goals.
Perhaps
restore ecosystem to historical
range of variation and ability to sustain self. (a) Kissimmee River, FL: undo channelization, restore soil layers in correct order. (b) Prairie restorationvery popular recently. Much original prairie remains along railroad; they were not plowed. (c) Early-succession grasses to restore damaged land (mining, urban). 2. Wetland restoration (a) Saltwater marsh restoration di cult because much more complex. (b)
1969 National Environmental Policy Act
mitigation require-
ment: if developer destroys wetland, must obtain or create to compensate. (c) Trying to construct wetlands to clean up runowetlands have some natural buering capacity. (d) Restored wetlands have been fertilized with treated waste water.
4.4.5 Sustainable Land-Use Strategies 4.5
Mining
1. Minerals are essential for our high standard of living. Almost everything uses them. 2. Mineral formation
22
(a)
Ore deposits
are formed when metals are concentrated in abnor-
mally high amounts by geologic processes. (b) As gravity condensed matter dispersed around into Earth, matter was heated. Iron and heavy metals sank toward molten center.
Not uniformly distributed because of selective dissolution, transport, and deposition. light rocks.
(c) Crust formed of lighter materials.
(d) Plate boundaries: crust is
i. Divergent: cold water gets heated by molten rock and leaches metals. Dissolved and deposited as sul des. ii. Convergent: rocks saturated with seawater are forced together, heated, and subject to intense pressure.
They partially melt.
Metals in magma mobilize. A. Hg distilled out of plate as plate moves downward. (e) Igneous processes i. Magma cools
→
minerals crystallize at dierent depths.
ii. Groundwater is heated and carries minerals.
Moves to cooler
rocks and deposits. (f ) Sedimentary processes concentrate materials for extraction. i. Water and wind segregate sediments. ii.
Placer deposits
are found in crevices or ssures. They are con-
California gold.
centrated mineral deposits formed by deposition of stream water that leaches metals from river basin.
iii. A shallow marine basin may be isolated by uplifting at its bound-
evaporates.
aries. The water eventually dries up, precipitating dissolved minerals called
(g) Biological processes: i. Phosphates: guano. ii. Iron ore: gray belts are unoxidized, red belts are oxidized. Apparently major iron deposition stopped when [O2 ] reached current level. iii. Organisms form many minerals, such as Ca in shells and bones. 31 identi ed as biologically produced. (h) Weathering processes concentrates some minerals in soil. More soluble minerals are selectively removed by biological processes. i. Al, Ni, Co are important soil minerals. ii.
Secondary enrichment
produces S
2−
from lower grades.
A. Near surface, primary ores and slightly acidic soil water, with oxygen, form H2 SO4 and sulfates of Ag and Cu. B. Migrate downward, leaching minerals.
23
enriching metal content of ores.
C. Below water table, where no more oxygen, deposit as
sul des,
3. Extraction (a)
Exploration
usually minimal impact, except for sensitive areas such
as wetlands, permafrost, arid lands. (b) As ores of lower grades are used, impact on resources increases. (c) Subsurface mines are much smaller, less visible, less waste rock. (d)
Surface mining
is cheaper, but has more direct environmental eects.
i. Large-scale environmental damage (beyond mine).
Change to-
pography. Dust pollutes air, even though attempts to control. ii. Leaching of trace chemicalsCd, Co, Cu, Pd, Mo can nd their ways into soil and groundwater. Runo ponds help, but do not eliminate. iii. Indirect: change nutrient cycling, biomass, species diversity, ecosystem stability. iv. Accidental discharges of stored waste. (e)
Strip mining removes surface layer of soil to expose coal (or other resource). Half of coal mined this way. i.
Acid mine drainage occurs when H2 O + FeS2 → H2 SO4 .
De-
bris left over from mining. (f ) Social impacts of mining: rapid urbanization, then rapid closing. (g) Minimizing impacts: i. ii. iii. iv.
Reclaim Stabilize contaminated soils Control air emissions. Prevent contaminated water from leaving. Treat waste. land.
often remove and dispose.
Neutralize acid with
lime.
v.
Perhaps with GM bacteria.
vi. Recycling: A. $50 B worth of metals are recycled. B. Iron/steel 90% by mass, 40% by value. C. Each ton saves: 1,136 kg iron ore, 455 kg coal, 18kg lime-
1 3 energy. D. Al recycling uses stone.
4.
5% energy.
Reserve is the portion of resource that is identi ed and can be extracted legally and economically at the time of evaluation. Resource is anything that can be extracted to obtain something useful.
(a) Concentration is everythingit determines usefulness.
24
(b) Except for Fe, nonmetals are used far more quickly than metals. (c) U.S. must import many strategic minerals (those necessary for military industrial complex) such as bauxite, Mn, graphite, Co, Sr, asbestos. i. Resulted in unlikely alliances between suppliers and consumers. Concessions on issues that would otherwise not happen. 5. Sustainability (a) Find ways to not use the mineral. Fiber optic obviates Cu; digital camera obviates Ag. (b) E ciency. (c)
R-to-C ratio:
namic.
R = known reserves; C = rate of consumption.
Dy-
6. Relevant laws and treaties (a) 1977 Surface Mining Control and Reclamation Act required restoration. Success is di cult and often dubious.
4.6
Fishing
1. Fishing techniques (a)
Bottom trawling
rolls a 60m trawl net on ocean oor, catching and
destroying everything in its path. 2. 44% of marine shing in upwelling zones. 3. Ironically, shing was one of the rst human activities to be scienti cally managed. (a) Wrong assumptions of logistic curve. (b) Tragedy of the Commons: little incentive to limit harvest.
eort. Predator sh
4. Currently not sustainable: increase in harvest Total population dropping.
(a)
accompanied by increase in
at 10% of preindustrial levels.
(b) Harvest levels peaked from 19701990. (c) 5.
Hunting
not likely to be sustainable: bison, whales.
Aquaculture
important protein source, growing.
Ancient practice in
China. (a)
Mariculture
(intertidal) much more productive than hunting for
oyster, mussel.
25
(b) Currently produce > 20%. 6. Laws and Treaties (a) 1972
Marine Mammal Protection Act sought to bring optimum
sustainable
population
rather than
yield.
International Whaling Commission's moratorium on commercial whaling protect 12 out of 80 species of whales.
(b) 1982
4.7
Global Economics
1. Tragedy of the Commons: individuals' personal share of
gain
from ex-
ploitation usually outweighs share of loss. Everybody wins in short term but loses in long term. (a) Forests (38% publicly owned), international water, Antarctica, air.
tion maximizes pro t.
2. Low growth rate means
not exploiting yields low pro t,
therefore
exploita-
Instead of slowly making money on the natural
growth rate, better to exploit all of the resources now and invest money. 3. Relative scarcity of resource aects value and price. Can you pro t from the resources harvested after your death? them extinct.
Then no interest in making
Do pro ts end when you die?
before you die.
Then harvest all you can
Can you earn your desired income from the resources
inde nitely? Then sustain. 4. Ralph d'Arge: developing countries did not share bene ts of Industrial Revolution, but now are sharing harms. They think that industrial nations, who have bene ted, should bear most future costs.
5
Energy Resources and Consumption
5.1 1.
Energy Concepts
Energy is the ability to accomplish work , which is force × distance.
2. A distinguishing feature of life is that it increases
local
order.
3. Units (a) Energy is measured in i. ii.
joule, 1 newton-meter.
Exajoule = 10 joules ≈ 1015 Btu (quad ). Newton is force necessary produce force of acceleration of 1 m/s2 18
to a mass of 1 kg. (b) Power is the rate of energy use ( second.
26
energy ) time
measured in
watt, 1 joule-
i. Multiplying watt by time (kWh) returns a unit of
power
energy
.
4. Amount of energy per unit times radiated from a body varies as the
5.2
of the absolute temperature of the body.
fourth
Energy Consumption
5.2.1 History 1. Greeks, Romans depleted wood
→
used solar power widely.
2. U.S.: wood peaked in 1880, coal peaked in 1920. 3. Exponential growth (consumption) from 19501980: 30 Since 1980,
→
→
80 exajoules.
100 exajoules, showing that new policies partially worked.
Production leveled o around 1970s. 4. Industrial energy consumption has leveled o since 1970s due to increased e ciency, cogeneration. 5. Car e ciency (avg.) rose from 14 mpg in 1970s to 28 mpg in 1996. Improvements slowed since then, largely because regulation loophole permits less fuel-e cient SUVs and light trucks.
5.2.2 Present Global Energy Use 1.
Cogeneration natural gas combined cycle power plant
can double e ciency by using waste heat. For example, generates electricity from both gas
turbine and steam turbine. 2.
Energy Policy Act of 2005 was rst national energy policy in over a decade: (a) Promote conventional energy to reduce reliance on foreign energy. (b) Promote nuclear power; build new ones by 2010. (c) Subsidies for alternative energy, make geothermal competitive, increases amount of ethanol in fuels. (d) Promote conservation: in federal buildings, for cars, credits for homeowners to install energy e ciency measures or automobiles. (e) Research to improve coal plants, goal for zero emissions, hydrogen cars, research shale and tar pits. (f ) Incentives to expand energy infrastructure and improve reliability.
3.
Hard path favors increased energy production while decreasing environmental impact.
Supporters argue that much environmental damage is
from developing countries using local energy, such as wood. 4.
Soft path
favors renewable resources, exibility, and match to uses to
increase second-law e ciency. Amory Lovins, champion, argues that most energy needs are of low quality, so expensive electricity is often wasted.
27
5.2.3 Future Energy Needs 1. Oil production expected to peak in 202050. A uence will be determined as much by energy conservation and e ciency as by production. 2. If
hard path
, then 120 exajoules by 2030. Else if
soft path
, 60 exajoules
(1991 prediction; overly optimistic, closer to 110 exajoules now). 3. To stabilize global warming, cut fossil fuels 50%.
5.3 1.
Fossil Fuel Resources and Use
Source rock
depositional basins
is nely grained organic matter (mostly plant) are buried in
sediments
at least 500 m deep.
Carbon must not
be completely oxidized.
(a) Pressure and temperature compresses sediment into oil and gas. (b) Light fuels migrate up to
reservoir rock
with lower pressure.
i. Porous; usually sandstone or limestone. ii. A
trap
A. B. C.
blocks upward ow.
Cap rock is ne-grained sedimentary rock. Anticline is an arch-fold that favors retention of fuel. A fault also traps the reservoir.
(c) Usually at young rock at plate boundaries. Exceptions: i. Texas ii. Gulf of Mexico iii. North Sea 2. 3.
Primary production pumps oil from well; only recover 25%. Enhanced recovery pumps stu (steam, water, gas) injected to push oil toward well.
4. Oil is 2nd most crust liquid, but 62% of proven reserves occupy 1% of oil eld. (a) Proven reserves = 1 trillion barrels; estimated 3 trillion barrels recoverable from remaining resources. (b) World consumption = 30 billion barrels/year.
consumption = 3 × discovery. Oil shale is ne-grained sedimentary rock with organic matter (kero-
(c) Today, (d)
gen).
Destructive distillation:
when heated to
retorted
500◦ C,
yields 60 L
oil/1 ton shale. U.S. has 2/3 of world supply. Produces more volume waste than mined because shale
28
crushed and heated.
(e)
Tar sands
are rocks or sands covered with tar oil, asphalt, or bi-
tumen. 75% in Alberta, Canada. Mine sands (di cult), then wash oil with hot water. Supplies 15% of North American oil production today. 5. Natural gas has only recently been seriously used for energy; used to be burned as waste, some places still do. 70120 year supply. Main transition fuel, since clean and releases less CO2 . (a) Coal-bed methane is methane stored in coal mines. (b)
7×
more can be stored in coal mine because of internal surfaces.
(c) 5 year supply at present rate can be recovered economically now;
3
estimated 20 trillion m . (d) Cheap to extract. Reduces methane emissions when mining. Disposal of saltwater waste is a problem. (e)
Methane hydrates exist 1000 m beneath sea oor: methane trapped in ice.
On land, known as
marsh gas.
Spontaneously erupt from
ocean oor. May have twice as much energy as all known fossil fuel reserves today, but mining will be di cult. 6. Coal swamps form from partially decomposed vegetation ( sea levels add sediment, compression peat into coal.
peat
). Rise in
(a) Most abundant fossil fuel; 250 years at current rate. (b) Rank: anthracite, bituminous (high sulfur), sub-bituminous, lignite. (c) Most polluting of fuels, in all stages. 7. Environmental disadvantages (a) Toxic brine is pumped with water; oil leaks. (b) Pollutants, including hydrocarbons and H2 S can be released into air. (c) Drilling muds (liquids injected into bore hole during drilling to keep it open) contain heavy metals. (d)
5.4
Re neries leak
(or spill).
Nuclear Energy
1. A neutron strikes
235
slowedto improve ssion. 2. Nuclear fuel (a) 1 kg UOx
≈ 16
moderated
U, producing ssion fragments and 3 free neutrons
and lots of energy. Chain reaction. Fast neutrons must be
MT coal.
29
(b) Only
235
U is ssile. Enrichment increases
[235 U]
to 3%.
3. Types of reactors (a)
Light water reactor
(U.S.) uses water as moderator.
i. Reactor core (fuel and moderator) encased in steel reactor vessel, then contained in reinforced concrete. ii. Fuel pins (enriched uranium pellets in tubes) packaged into fuel subassemblies.
critical Coolant must remove heat at the same rate it is produced. meltdown Pebble-bed reactors iii. A minimum amount of fuel keeps reactor
self-sustaining.
iv.
Else
core gets so hot it melts and breaches containment.
(b)
are gas-cooled and have billiard-sized pebbles as
fuel. Graphite shell with sand-grain particles of UO.
i. Mixed with unfueled graphite spheres to control heat. ii. Continuously refueled.
Always at optimal productionsafety
feature.
iii.
Passive stability Modular
means a reactor does not fail/meltdown due to
pump failure. iv. (c) (d)
each core 120 MW. 25% more e cient.
Burner reactors consume more ssile material than they produce. Breeder reactors make low-grade or waste U ssile. Can last 2,000 years.
4. Nuclear fusion:
2
H
+3 H →10
n
+42 He.
(a) Need very high temperature and density to form plasma.
energy released by fusion must exceed energy required to maintain plasma.
(b) Plasma must be con ned and
(c) Nearly in nite fuel reserves; cheap to produce. 5. Environmental impacts (a) Uranium mines produce radioactive waste. Mine tailing have been used for structures. (b) Enrichment produces waste. (c) Concern that waste cannot be isolated for required period of time. (d) Nuclear plants must be decommissioned. May be the highest cost. (e)
Radioisotopes can nd their way into food chain; circulate like their normal isotopes.
6. Radioactive Wastes and Human Healthcauses cancer.
30
(a) Units of radioactivity i. ii.
Curie Becquerel
(Ci) =
37 × 109
nuclear transformations/sec.
(Bq) = 1 radioactive decay/sec.
3
iii. For isotopes, pC/L (picocurie per liter), or Bq/m .
rads rems. gray Energy retained by tissue after radiation exposure. sievert absorbed dose × relative biological eectiveness.
iv. Actual dose of radiation:
and
A. SI
(Gy) = 100 rads = absorbed dose.
B.
(Sv) = 100 rems = eective equivalent dose =
v. Gamma rays: roentgen (R) or SI coulombs per kilo (C/kg). (b) American average 24 mSv/yr. i. 66% natural (0.35 mSv/yr is human;
40
K and
14
C).
ii. 33% is other, mostly medical. (c)
α
must be very close to cell. Blocked by paper. Dangerous if inhaled
or ingested; radiation absorbed by tissue. (d)
β
particles are electrons.
Block by thin metal or block of wood.
Moderately toxic; mostly absorbed when ingested. (e)
γ
rays require a meter of concrete or centimeters of lead.
When
ingested, some radiation exits body. (f )
Chronic
radiation health problems are not well known or understood.
7. Accidents: acceptable risk of 0.01%/yr is unacceptable if there are 1,000 plants. Also, often not planned to respond in accidents. (a) Three Mile Island: valve malfunction + human error. i. Containment structure functioned as designed. ii. 1 mSv released into atmosphere; surrounding 0.012 mSv. iii.
But
, on site, very high radiation: 12 mSv/hr.
(b) Chernobyl:
human error caused meltdown; explosion blew top of
building o, graphite burned. Radioactive particles rise into air. i. 237 con rmed radiation sickness; 31 deaths. ii. Did not tell world until 2 days later when confronted by Sweden's measurements of increased radiation. iii. 24,000 estimated to have received 430 mSv. A. Expected (based on Japan) 122 spontaneous leukemias. B. No signi cant increase yet, but possibly future. iv. Childhood thyroid cancer increase. v. Outside 30 km, probably negligible eect. A. Vegetation with 7 km dead or severely damaged.
31
(c) In last 34 years, about 10 accidents released radiation. 8. Radioactive wastes (a)
Low-level wastes in not hazardous is properly disposed.
closed because they have polluted groundwater.
solutions, sludges, acids, slightly contaminated equipment.
(b)
3/6 sites
Residues,
Transuranic waste is human-made materials heavier than U. Mostly from weapons.
(c)
High-level wastes is spent fuel, military reprocessing waste, weapons materials. i. Currently stored, mostly at commercial reactors. ii. Geological disposal controversialsome don't think it should be buried. iii.
Nuclear Waste Policy Act of 1982 initiate disposal program. A. 1987 amendment and Energy Power Act of 1992 specify deep underground repository: Yucca Mountain. B. Could receive waste starting 2010.
impact of heat generated by
C. Need to evaluate earthquake, volcano, groundwater, escape
waste
from deteriorating containers,
, geological processes that control transfer of radioac-
tive material. (d) Waste isolation pilot plant in Carlsbad, New Mexico: i. Rooms excavated in rock salt (easy to mine) store wastes. ii. Slow- owing salt naturally seal in 75200 years. (e) Sites that have been stable in past may not be stable in future. 9.
5.5
Energy Policy Act of 2005 advocates increase of nuclear power. Hydroelectric Power
1. Dams are multifunctional, but functions may not be harmonious (draining for agriculture con icts with high levels for high power and recreation) and dams have many environmental impacts: (a) Lose land and resources to make lake. (b) Trapped sediment ( where needed.
silting
) limits life of reservoir and prevents deposit
(c) Change entire river downstream. (d) Fragment ecosystems. (e) Increases evaporation
→
change local climate.
32
(f ) High pressure nitrogen can kill sh when swimming under waterfall as gas expands (bends). 2. Most good sites already dammed; not expected to grow in U.S. 3. Dams also give false sense of security: oods can occur from tributaries, dams may fail, and higher-than-designed-for- oods may occur. 4. Good dam sites are often good scenic nature sites. 5. Dams are 6.
expensive.
Their cheap water is
Water power is ultimately solar power.
subsidized.
7. 10% of U.S. power. Majority in Norway, Canada. 20% worldwide. 8.
Pump storage:
pump water into reservoir during low demand; ow out
during high demand. 9. Several dams have been removed or have been planned for removal. Many old ones are not useful at all.
If lots of sediment, most remove slowly
to minimize impact. May be many times more expensive to remove dam than to build it. 10. Colorado river is most heavily managed river; 80% of water in reservoirs behind Glen Canyon Dam and Hoover Dam. (a) River
has
been tamed: average ow increase, high ow decreased.
(b) Natural oods helped restore ecosystem, as did experimental oods.
3
(c) Treaty supplies 1.845 km
of water to Mexico. Very salty.
i. Desalinization plant built in Yuma on standby after its canals were ooded. ii. Coachella Canal can provide Mexico with water. iii. All American Canal delivers water to San Diego. Leaks billions of gallons that recharge groundwater used by Mexican farmers. Proposed concrete lining has been heavily impugned.
5.6
Energy Conservation
accomplished.
1. E ciency: food measured in
2.
First-law e ciency = (a)
energy stored
energy delivered . energy supplied
Second-law e ciency =
; consumption measured in
work
Average 50% in U.S.
minimum energy necessary . energy used
Average 1015%
in U.S. i. Lighting candle with match is more e cient than with acetylene torch.
33
ii. Water can be heated better by sun, not humongous furnace ames.
(b)
Thermal e ciency
is the maximum e ciency of a heat engine (such
as power plant, internal combustion); discovered by Sadi Carnot. Modern power plants, about
5.7
1 3.
Renewable Energy
1. Solar energy arrives at 7,000 times current demand. 2.
Passive solar energy uses architecture to adjust to seasonal changes. (a) South-facing building and windows and overhangs shade summer sun but allow winter sun to penetrate. (b) Walls can absorb energy then radiate into rooms. (c) Deciduous trees block sun during summer but allow sun during winter.
3.
Active solar energy requires mechanical power to circulate a uid from solar collection site to usage site. (a)
Solar collectors have a glass plate and black background with tubes ◦
in between. Water heated to 3898 C. (b)
Evacuated tube collector
has each tube pass through a larger tube to
reduce heat loss.
4.
Photovoltaics are the fastest-growing source of energy at 35% annually. (a) Standardized modules; build the system you need. (b) Dierent electronic properties of semiconductor layers cause electrons to ow into wires when hit by photons. (c) Developing countries: cheap, simple, o-grid rural electricity. (d) Springerville Generating Station in Tucson produce 24 MW.
5. Power tower concentrates sunlight to a central collector to boil water. (a) Can store heat with liquid salt. (b) By 2030, estimated by be economically competitive. 6. Luz International Solar Farm: synthetic oil pumped through solar collectors; boil water; steam superheated by natural gas. Combination allows uninterrupted power. 7. Environmental disadvantages of solar: (a) Dispersedproblem for centralized power. Need lots of land.
34
(b) Metals, plastics, and uids for equipment (esp. photovoltaics) may be toxic; production releases greenhouse gases. 8. Hydrogen is clean and can be burned like fossil fuels. (a)
Fuel cell works like battery to generate electricity by oxidizing H2
e ciency.
and capturing e
−
in external circuit (redox).
Increase second-law
i. Electrolyte solution; electrodes separated by Pt membrane. (b) Most economical way to produce hydrogen: H2 O + CH4
→ C + CO2 +
H2 . (c) Can be used to buer electrical generation. 9.
Tidal power
dam opening, then release water on turbines when tidal
movement increases/decreases ocean height su ciently. (a) Few locations have su ciently strong tides. (b) Can damage ecosystems of estuaries/bays. (c) Rapid lling and emptying of the bay damages intertidal habitats. 10. Wind power (a)
Winds
are produced by dierential heating of Earth's surface, result-
ing in air masses with dierent heat and density. i. Wind concentrated on mountain top or mountain pass. (b) Small mills (for farm) produce 1 kW. Modern windmills 6075 kW. i. High-tech ones 100 m, 30 stories, 35 MW. One is in Germany. (c) Wind power currently cheaper than natural gas, approaching coal. (d) World total 48,000 MW (34,000 MW in E.U.). i. 1 large fossil or nuclear = 1,000 MW. ii. 1% of total electricity. (e) High potentialmany countries have more potential than current use.
11.
Micro-hydropower
is best in mountains. Evaluate case-by-case.
(a) Prone to being lled by sediment. (b) In large scale, can have signi cant environmental detriment. 12.
Biofuels
are organic matter, burned or converted (gasify, distill), then
burned. (a) 35% of developing countriesusually rewood.
35
(b)
Digestion
bacteria digest matter to produce methane.
(c) Land lls, wastewater treatment plant can produce biogas (mainly methane). i. China, produced in sewage treatment. ii. India, produced locally from cow manure. (d) Waste incineration releases pollutants, as not all hazardous trash can always be removed. (e) Land unsuited for food crop can grow biomass crop (like trees). (f ) By 2030, biomass can produce 100,000 MW (12%), using 2/5 of banked farmland. 13.
Geothermal energy harnesses natural heat from earth's interior. (a) 9,000 MW0.15%. (b) Competitive with other sources. (c) At plate boundaries, heat ow is unusually high. (d) Hot geothermal system (>
80◦ C)
resource base > fossil + nuclear.
i. Hydrothermal convection: steam and/or hot water pumped to depths to transfer heat to surface. ii. Geysers Geothermal Field produce 1,000; near San Francisco. (e) Lower temperature systems can be used for heating. i. Groundwater is geothermal: at 100 m, groundwater is
13◦ C
and
can heat/cool homes. (f ) Environmental impact i. Releases some CO2 , SO2 . ii. Thermal pollution. Hot wastewater can be corrosive and saline. (g) Future i. Known reserves 20,000 MW, 10% for West. ii. Undiscovered potentially
6
4×.
Pollution 1.
6.1
Heavy metals include Hg, Pb, Cd, Ni, Au, Pt, Ag, Bi, As, Se, V, Cr, Tl. Pollution Types
6.1.1 Air Pollution 1. Particulates are
small dust particles (including asbestos).
heavy metal.
36
Sometimes
(a) Coal power plants. (b) Industrial boilers. (c) Cars. 2.
Stationary pollution includes point sources (single sites), fugitive sources (open areas
exposed to wind
), area sources (well-de ned area that has sev-
eral sources).
3. Eects include damage to vegetation, increased susceptibility to diseases and pests, disruption of reproduction. In humans, poisoning, cancer, birth defects, irritation, susceptibility to viral infections, heart disease, aggravation of respiratory diseases. 4.
Criteria pollutants are 6 most common ones. (a) Sulfur dioxide is oxidized into sulfate, forming sulfuric acid. coal, oil re ning, industrial processes.
Bleaches leaves.
From
Increases
chronic respiratory disease, shortening of breath. Reduced 50% since 1970s. (b) Nitrogen oxides (most commonly NO, NO2 ) contribute to smog and
2−
ion NO3 , reducing visibility. Emitted from stationary and mobile sources. Acid rain. May suppress plant growth; may be bene cial at low concentrations. (c) Carbon monoxide bonds
250×
more easily to hemoglobin than does
oxygen. i. Worst for heart or respiratory disease or at high altitudes. ii. 10% man-made. Most emissions from tailpipes. (d) Ozone/photochemical oxidants result from interactions between NO2 and sunlight. i. Unstable, so oxidizes better than does oxygen. ii. Retards plant growth at low concentrations; kills leaves and plants at high concentrations.
Lungs decrease elasticity, scars
in airways. iii.
Peak ozone level
is one of the best indicators of air pollution.
(e) Particulate matter (PM 10) is composed of particles (<
2.5µm)
< 10µm.
PM 2.5
is of special concern because they are absorbed through
lungs into bloodstream. i.
Total suspended particulates
measures this pollution. Much higher
in cities of developing countries. ii. 29% of human mortality in cities. iii. Dust can suocate plants. Large particulate pollution (e.g., from construction) can damage entire ecosystems.
37
iv.
Global dimming cools atmosphere.
Jet travel is a signi cant
cause.
(f )
Lead
5.
or
is emitted through leaded gasoline, which protects engines.
Transported as particulate
uptaken by organisms.
Primary pollutants are emitted directly into air. (a) CO (58%), VOC (11%), NOx (15%), SOx (13%), particulates (3%). (b)
Natural
6.
Exceed human pollution.
emissions: SO2 from volcano, H2 S, wild res, hydrocarbon
seeps: La Brea Tar Pits.
Secondary pollutants result from reaction between primary pollutants and normal atmospheric compounds.
7. Acid rain can precipitate or be deposited as sulfate and nitrate, acid anhydrides. (a) Can travel
very
far:
1 3
> 500
mi,
1 3 [200, 500] mi.
(b) CaCO3 (limestone) can buer acids; granitic rocks cannot. (c) Forests: trees weaken, die
→
less habitat; leaves fall o
→
change
surface microclimate. (d) Lakes: interferes biologically, dissolves nutrients
→
ow out and are
lost. Algae die. i. Acid leaches metals from soils. Al hazardous to shclog gills. Heavy metals!
(e)
Acid fog
occurs when water vapor, mixed with pollutants, condense
near ground around smog particulates. Drops of acid may be left as fog dissipates and can be inhaled deeply within lungs. 8. Air toxics are hazardous at low concentrations; many carcinogenic. Classi ed into gas, metal, organic, then whether carcinogenic. (a) H2 S from re neries and smelters, or geysers, swamps, bogs. (b) HF from Al production, coal gasi cation, burning coal. toxic. Can damage grazers because plants are exposed. (c) Methyl isocyanate burns on contact (irritation). violent coughing, swelling of lungs,death.
Extremely
Few ppm causes
Used in pesticides.
In
Bhopal, India leaked from tank. Catastrophic. (d) Volatile organic compounds (VOC) are used as solvents. Hydrocarbons react to produce smog. Cars. Lowered 50% since 1970s. (e) Benzene is solvent and gasoline additive. (f ) Arcolein produced in industrial combustion of petroleum. Extremely irritating.
38
9.
Heat island occurs due to burning fuels and solar collection of buildings and pavement.
10.
Temperature inversions
Caps on pollution altitude. (a) Coast:
occur when warmer air is above cooler air.
descending warm air forms semi-permanent inversion.
Sea
breeze pushes pollution towards canyons. (b) Valley: cloud cover decreases temperature at surface and increases temperature in clouds, forming warm air.
At surface, dew point
(temperature where vapor condenses) may be reached (c) 11.
Chimney eect:
→
fog.
polluted air may spill over mountains.
Smog (a)
Photochemical
(L.A., brown air): NOx emitted by cars accumu-
late; sun breaks down to NO + O; O + O2
→ O3 .
Organic compounds
react with NO to increase NO2 . Ozone maximum at noon. (b)
Sulfurous (London, gray air, industrial).
From burning fossil fuels.
12. Indoor air pollutants (a)
Legionella pneumophila
, pond-water bacteria can spread to air con-
ditioners. Cause Legionnaire's disease. (b) Molds may release toxic spores. Chronic in ammation and scarring of lungs.
1 2 of all health complaints.
(c) Pesticides. (d) Formaldehyde used in insulation, manufactured wood.
Emit gas.
(e) Dust mites, pollen. (f ) Environmental tobacco smoke exposed to workers may be equivalent to 10 cigarettes per day. (g)
Radon is natural: lead-206.
α
radium
→
radon
decays.
i. Estimated 10% of lung cancers.
→
polonium-218
→
lead-214
→
Very large threat if true.
ii. Synergistic with smoking. iii.
α
particles break DNA strands.
iv. Radon enters through rock and soil into basement, dissolved in groundwater, or contaminated construction materials. v. Techniques to remove: A. B.
Gas permeable layer (often gravel) beneath oor. Plastic sheeting on top of gas permeable layer prevents radon from entering.
C.
Sealing and caulking in foundation oor. 39
D.
Vent pipe from gas permeable layer to roof.
(h) Often more highly concentrated. i. Many potential indoor sources. ii. Energy e ciency = sealing building.
Cannot dilute pollutants.
(i) Control: i. ii.
Ventilation: use more fresh air; open windows. Source removal: restrict or prohibit use of certain
material,
ban smoking indoors. iii.
Source modi cations:
change designs (more energy e cient,
use non-polluting materials); apply barriers (coat lead paint). iv.
Air cleaning:
ltering.
v. 13.
Chimney eect occurs due to temperature gradient between indoor and outdoor. (a) If inside is warmer, warm air rises and
draws in
air from lower. En-
vironmental tobacco smoke can be drawn in from outside. 14. Sick building have two types: (a)
Building-related illness (BRI) has identi able problems, such as pathogenic molds or bacteria.
(b)
Sick building syndrome (SBS) cannot be traced.
Non-pollution
factors (environmental stress, labor-management relations) may contribute. 15. Remediation and reduction strategies (a) (b)
Conservation e ciency. Capture particulates Cover Recirculate exhaust Dilute air-fuel mixture Catalytic converter: and
from point sources in settling chambers or col-
lectors.
(c) (d) (e) (f )
waste or dirt piles to reduce dust. to reduce NOx . less NOx , more hydrocarbons.
decompose hydrocarbons and oxidizes CO.
i. Old cars pollute more because people don't take care of pollution devices.
Charge fees Washing ii.
(g) (h)
for pollutionrequire annual testing.
coal removes pyrite, but organic carbon remains.
Coal gasi cation produces expensive synthetic gas. 40
Expensive.
(i)
Scrubbing: 1 2 H2 O
+ CO2
calcium removes sulfur:
CaCO3
+
SO2
→
CaSO3
·
(or CaO).
16. 4 processes remove particles and chemicals for air: (a) Sedimentation: heavier-than-air particles eventually settle out. (b) Rain out: precipitation physically or chemically removes substances. (c) Oxidation. (d) Photodissociation: energy from solar radiation breaks bonds. 17. Coal-burning power plants produce 70% of SO2 , 30% of NOx , 35% of CO2 . 18.
Clean Air Act Amendments of 1990 are comprehensive regulations. (a) 50% cut in SO2 achieved. (b) 2 Mton reduction in NOx more di cult because cars emit most. (c)
Permits
comprise total amount of allowed pollution. Environmental-
Makes pollution expensive.
ists can also buy permits to prevent them from being used, but not a major factor. (d) Goal: end
all
CFC and chlorine chemicals by 2030.
(e) National Ambient Air Quality Standards as
minimum acceptable level
set to reduce health hazards in old and youngmost susceptible. Supreme Court unanimously upheld standards. 19. Economic impacts: incremental cost diers. Much more expensive for Al plant to reduce emissions than for utilities. Some argue stricter standards for utilities and fewer for Al. Others prefer taxes or pollution vouchers same environmental eect but more cost eective because driven by market pressure.
6.1.2 Noise Pollution 1. Eects (a) Up to 60 dB is safe. (b) > 80 dB is potentially dangerous. (c) 140 dB is threshold of pain; 180 dB is injurious.
hour.
(d) Lawn mower, motorcycle damages after after
1 2
8 hours.
110 dB loud music
(e) 5060 dB noise interferes with sleep; fatigued awakening.
41
6.1.3 Water Pollution 1. Thermal:
↑
→↓ [O2 ]. ∆1.5◦ C.
heat
only tolerate
Warmer water decreases sh tness; some may
2. Types include heavy metals, sediment, radioisotopes, heat, fecal coliform bacteria, P, N, Na, pathogens. (a) Surface water is not immune to outbreaks. tated Milwaukee: it is resistant to chlorine.
Cryptosporidium Cryptosporidium potential.
devasmust
be ltered, but it doesn't usually enter water supply. (b)
Fecal coliform bacteria is a measure of disease
Usually
harmless bacteria in animal intestines. Pathogens are more likely to be present where more feces is deposited. i.
E. coli
E. coli
can be deadly. Walkerton, Ontario: 5 died, 500 ill because
storm waters contaminated wells with report.
and utilities did not
(c) N, P: from fertilizer, detergent, wastewater treatment.
eutrophication (human caused).
Cultural
i. Promotes plant, cyanobacteria, and algae growth. ii. Algae form surface mats
→
kills stu below.
iii. Decomposing bacteria grow, remove oxygen, eventually lots of stu dies. iv. v.
Eutrophic lakes Oligotrophic lakes
have naturally high levels of nutrients. have naturally low levels, pleasant water.
vi. Coasts, reefs may also suer from eutrophication: Great Barrier Reef, Hawaii. (d) Oilnormal shipping probably releases most pollution.
Long-term
eects unknown. (e) Sediment (small rock and mineral fragments) is by volume highest level of pollutant. i. Agriculture increases erosion.
Conservation cannot eliminate
loss.
but
ii. Urbanization even greater: struction,
large amounts erosion during con-
on-site control measures can be eective (35% re-
duction in a Maryland sediment control program). (f )
Acid mine drainage
is water with lots of H2 SO4 formed from
weathering of pyrite. i. Abandoned mines are problematic because groundwater is non longer pumped out, so it can ood and over ow. 3. Sources include all sectors of society:
42
(a) Surface water occurs when in ow of pollutant exceeds natural capacity to remove, convert, or dilute it. i. Runo: urban (oil, chemicals), agricultural. ii. Accidental spills, release of radioactive stu (from accidents). iii. Leakage from storage sites. iv. Air fallout. v. Sediment from agriculture and construction sites.
1 2 of domestic water supply. It is actually easy to pollute. Channels for groundwater are small, so dilution
(b) Groundwater is the source of opportunity is limited. i.
Leaks
waste disposal, buried pipes. Estimated that 75% of haz-
ardous waste disposal sites are polluting groundwater. Land lls over porous soils pollute water quickly. ii.
Seepage
: acid water and waste from mines, cesspools/septic sys-
tems, spills, radioactive materials. iii. Saltwater intrusion in coastal aquifers: when water is pumped, it no longer ows out into saltwater aquifer, allowing salty groundwater to in ltrate. 4.
Biochemical oxygen demand (BOD) for organic
decomposition
.
is amount of oxygen required
Amount of oxygen consumed by decompser
microorganisms.
(a) Inversely related to dissolved oxygen. (b) 5 mg/L is threshold for water pollution of DO. 5.
Wastewater treatment deals with addition of suspended solids,
salts,
nutrients, bacteria in water due to human use. (a) Septic-tank separates solid and liquids and digests (biochemically change) organic matter. i. Water then moves into absorption eld/drainage eld and seeps into soil.
land. Failures
ii. Further treated by oxidation and ltering.
iii.
Not suitable for all
occur when tank is not pumped, for poor drainage allows
wastewater to rise to surface. (b) Wastewater treatment plants remove BOD and chlorinate bacteria. i.
Primary treatment involves screens
grit chamber tank Digester material,
primary sedimentation
to remove large oating
to remove rocks,
where particulates settle to form sludge.
A.
processes sludge. Relatively new.
43
B. Removes 3040% of BOD.
ii.
Secondary treatmentactivated
sludge method (most com-
mon). A.
Aeration tank nal sedimentation tank. Activated sludge Final sedimentation tank
mixes wastewater with air and some sludge
from
B.
is rich in aerobic bacteria, which consume
BOD.
C.
settles sludge out (again).
Most
sludge goes to digester.
D. Removes 90% of BOD.
iii.
Advanced wastewater treatment use sand lters, carbon lters, chemicals to remove speci c pollutants such as N, P, heavy metals.
iv.
Chlorine produces toxic by-products.
v. Methane is released by digestion; used as fuel or burned as waste. vi. If sludge isn't polluted, used to improve soil, else land lled. 6.
Wastewater renovation and conservation cycle involves using treated wastewater to irrigate, then allowing water to
renovate
(natural puri ca-
tion through slow percolation in soil), recharging groundwater, and reuse of groundwater. 7.
Resource recovery
wastewater plants capture methane and use plants grown
in controlled environment (sell owers to nance operation) in lieu of secondary treatment. More greenery can purify water even more. 8. Wastewater can be applied to isolated wetlands.
Promote growth and
reduce downstream BOD. 9. 1792/1977 Amended Clean Water Act (Federal Water Pollution Control Act) provides billions in grants for sewage treatment plants, encourages innovation, including alternative wastewater treatment and aquifer recharge. 10. Other relevant laws: (a) 1956
Federal Water and Pollution Control Act Fish and Wildlife Coordination Act
enhances water quality
and controls pollution. (b) 1958
mandates conservation mea-
sures with U.S. Fish and Wildlife Service for dams, power plants, and ood control. (c) 1969
National Environmental Policy Act
requires
impact statements
prior to federal actions that signi cantly aect environment: dams, channelization, power plants, bridges. (d) 1970
Water Quality Improvement Act
expands 1956: control oil and
hazardous waste; research for Great Lakes and mine drainage.
44
Federal Safe Drinking Water Act Comprehensive Environmental Response, Compensation, and Liability Act Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act Water Quality Act
(e) 1974
sets containment levels for
pollutants and pathogens. (f ) 1980
establishes revolving fund (Superfund) to clean up haz-
ardous waste sites to reduce pollution. (g) 1984
regulates underground gasoline storage
tanks. (h) 1987
establish policy to control non-point pollu-
tion. Led to development of state management plans to control.
6.1.4 Solid Waste 1. Types. (a) 35% paper (b) 12% yard trimmings (c) 12% food scraps (d) 11% plastics (e) 8% metals (f ) 7.4% rubber, leather, textiles (g) 5.3% glass (h) 5.8% wood (i) 3.4% other
toxic.
i. Infectious wastes should be sterilized and are
ii.
not considered
Hazardous waste is produced 700 Mton/year in U.S. A. 50% chemical industry. B. Electronic, petroleum, coal each 10%. C. Destroyed buildings. D. Tons of abandoned waste sites.
1,000 may threaten public
health and environment. E. Management of hazards may be most serious environmental problem. 2. Hazardous waste legislation (a)
1976 Resource Conservation and Recovery Act (RCRA) identi ed hazardous wastes and life cyclescradle to grave management.
45
(b)
1980 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) de ned policies and procedures for release of hazardous substances into environment. i. List of sites where hazardous substances likely or already impacted environment. ii.
Superfund
to clean up worst cases.
iii. 1984 and 1986 amendments: A. Improve standards for disposal and cleanup. B. Ban disposal of certain chemicals: dioxin, PCB, solvent. C. Timetable for
phasing out
disposal of all untreated liquid
hazardous waste in land ll or surface impoundment. D. Increase Superfund. E.
Environmental audits permit defense against liability.
tine.
old maps, photographs, reports, drilling, sampling.
Now rou-
Study
F. Toxic 500 become public. Pressure industries. 3. Disposal: (a)
Composting
is rapid partial decomposition of organic matter by
aerobic organisms. Popular in Europe and Asia due to intense farming. Large-scale in mechanical composters. (b)
Incineration
burns at temperatures high enough to consume all
◦
◦
combustible material (900 C1,000 C). i. Ideally 7595% reduction. ii. Practically 50% due to maintenance and waste supply problems. iii. Can supplement other fuels. iv. Pollute air. Trapping pollutants expensive. Need subsidies. Not optimal investment. (c)
Open dumps have waste piled and unprotected.
Closed and banned
in U.S. and many other places. i. Sometimes ignited. ii. Other places periodically compacted. (d)
Sanitary land ll
waste with soil every day or more often. i.
is designed to concentrate and contain.
Covers
Leachate is water percolating into refuse that carries pollutants and bacteria.
ii. Siting is everything.
Arid, impermeable places with low water
table. iii. Often located in poor and minority places. iv.
Monitoring involves continual sampling (even if land ll abandoned) of water and gas at special monitoring wells.
46
v. Entry of pollutants into environment: A. Gas release. B. Heavy metals retained in soil and uptaken by plants. C. Soluble materials move to groundwater. D. Polluted groundwater can seep into surface water. E. Wind blows toxins away.
vi.
Multiple barriers Vital to prevent leachate from reaching groundwater, where cleanup will be very expensive. include clay and plastic liners to limit leachate,
drainers to collect leachate, gas collection, groundwater monitoring.
vii.
Resource Conservation and Recovery Act of 1980 strengthen
and standardize design, operation, and monitoring of sanitary land lls. Fail
→
close.
4. All methods of hazardous waste disposal causes some environmental disruption. (a)
Secure land ll con nes waste, controls, collects, and treats leachate, and detects leaks. i. Drains concentrate leachate to collection basin. ii. Animals can chew or burrow through impervious liners. iii. Some argued no such thing as secure land ll.
(b)
Land application is intentional spreading of waste on land. able stu, like oil waste.
breakdown.
i. Micro ora (microorganisms in soil) attack material in
Biodegrad-
microbial
ii. Restricted to top 1520 cm. (c)
Surface impoundment uses depressions or excavations.
Aeration
pits and lagoons. Seepage. Controversial; many closed. (d)
Deep-well disposal injects waste to place isolated from aquifers porous rock sealed by impervious rock. i. Oil- eld brine. ii. Not quick and easy solutionfew sites, must monitor.
5. Alternative methods for toxic waste (a) Recover valuable materials for future use in waste. (b) Neutralization, oxidation, and separation of heavy metals. (c) Incineration can destroy hazards, but some may escape as pollution. 6. Ocean dumping and pollution along shipping lanes
47
(a) Most pollution in the most productive parts of ocean. (b) Threaten sheriesshell sh contain polio- and hepatitis-causing organisms. (c) Algal blooms kill almost all marine life in area. (d)
Microlayer
, top 3 mm, extremely fragile. Phytoplankton, sh larva
here.
i. Heavy metals 101,000 more concentrated here. (e) Plastics oat and accumulate in convergent currents.
vergence.
i. Northwestern Hawaiian Islands, very remote, is one
zone of con-
ii. 80 tons of marine debris collected there. iii. Birds eat plastics. Rings seal mouths. 7.
Industrial ecology is the study of relationships among industrial systems
of place.
and linkages to natural ecosystems.
Essentially, waste is a resource out
As extraction costs increase, nancial feasibility of reusing and
recycling increases. (a) For example, coal power plant heats homes, scrubs SO2 to make gypsum, CO2 sequestered and pumped to greenhouses, ash used to surface roads. (b) Canberra, Australia hopes to achieve zero-waste by 2010. 8.
Integrated waste management
composting, land lling, incinerating.
includes
reuse, reduction, recycling,
(a) At least 50% waste stream can be reduced: i. Better packaging (10%) ii. Large-scale composting (10%) iii. Recycling (30%). A. U.S. recycles 30% of waste stream. B. 50% reached in some parts of U.S. C.
Intensive recycling Must develop market for recycled products.
can reduce 8090%; pilot program 84%.
D. 50% of U.S. steel from scrap. E.
(b) Using sewer sludge is widespread, but getting rid of toxins is di cult. i. Separate urban and industrial wastes. ii. Require factories to pretreat their waste. (c)
Materials management is resource conservation. i. Eliminate subsidies for virgin material and incentivize use of recycled.
48
ii. Fine poor material management processes. 9.
Pollution prevention (P-2):
Wisconsin cheese factory deposited 2,000
gal of salt water into landscommon for corporations that cannot discharge into municipal treatment plantsand damaged crops. DNR limited salt discharge. Factory developed evaporator, which reduced waste by
We are moving away from regulating disposal to eliminating as much of it as possible.
75% and decreased salt purchases by 50%. Recovered costs in 2 months.
6.2
Impacts on the Environment and Human Health
6.2.1 Hazards to Human Health 1. Synergism: toxins acting simultaneously
often unknown.
2.
may be
>
P
parts.
Eects
Environmental risk analysis (risk assessment) is the determination of health hazards to people exposed to pollutants and possible toxins. (a)
Identify hazard Dose-response assessment Exposure assessment
(whether exposure is detrimental).
Observe other
humans, animal testing, cellular/molecular research. (b)
. Administer varying doses to humans or
animals. Di cult. Doesn't prove causality. (c)
. How many exposed, how much area contam-
inated, ecological gradients, length of exposure? Di cult like doseresponse. (d) 3.
Risk characterization
. Conclude health risks based on exposure.
Asbestos are ber-shaped minerals. (a) Fibers embed in lung tissue (b)
White asbestos
→
Asbestosis
is related lung condition.
cancer.
(chrysolite) is not particularly harmful. 95% of U.S.
i. No recorded nonoccupational disease. ii. Belief that much removal was unnecessary.
(c) 4.
Blue asbestos
Lead
(crocidolite) very harmful.
is apparently biologically useless but impacts every system, espe-
cially nervous system and in small children. (a) Poisoning of patricians may have contributed to Roman fall. (b) In children, may promote antisocial/criminal behavior. 5.
Electromagnetic elds have been suspected of increasing cancers, but question not yet answered.
49
6.
Voluntary exposure is commonly smoking, drinking, and drugging.
7. Acute eect occurs soon, usually large exposure. Chronic opposite. 8.
Dose response
means the eect of a chemical depends on the dosage
(concentration).
harmful. harmful
(a) (Very) low concentrations (b) High concentrations i. ii. iii.
, eventually
lethal
.
LD-50 is dosage where 50% of population dies. Crude. ED-50 is dosage that causes desired eect in 50% of population. TD-50 is dosage that is toxic to 50%. Often reduced enzyme activity, decreased reproduction, other speci c symptoms.
iv.
Therapeutic index =
LD-50 ED-50
and
↑=
safer.
(c) Curve crests where maximum bene t occurs (plateau). (d) Threshold values unknown for most substances, especially transition from bene t to harm.
6.2.2 Hazardous Chemicals in the Environment 1. Biomagni cation. (a) Cd: coal (b) Hg: Hg 2.
→
2+
ash
→
plant
→
herbivore
bacteria
−−−−−→ [CH3 Hg+ ]
→
carnivore (5060×)
accumulates more, stronger eect.
Persistent organic pollutants are now banned. (a) Example i. PCBs (heat-stable oils). ii. Dioxin, perhaps most toxic man-made chemical. Byproduct of chlorine combustion in herbicide synthesis. A. Damages wildlife in
very
small amounts.
B. Human impact controversial. (b) Often contain Cl. (c) Do not biodegrade. (d) Fat soluble; likely to accumulate. (e) Able to be transported long distances in wind, water, sediment. (f )
Hormonally active agents i.
Atrazine
(herbicide) feminizes frogs.
ii. Detriment reproductive viability. 3. Ecological gradients can be de ned by distance to pollution source.
50
4.
Tolerance is ability to resist or sustain stress due to toxin or environment. (a) Behavioral. (b) Physiological: body adjusts.
Does not mean damages ceases.
i. Detoxi cation. ii. Transport of toxin to non-harmful place (fat). (c) Genetic tolerance: selection.
6.3 1.
Economic Impacts
Cost-bene t analysis.
of life, not length.
(a) Risk of death from pollutants is low.
quality
Lowering air pollution increases
(b) Risks that aect a small proportion of people are more acceptable. (c) Novel risks are less acceptable. (d) More desirable activities carry greater acceptable risk. Sports, recreation vs. working.
But do we value length
(e) RAND study nds that direct measures (i.e., not bettering the envi-
of or quality of life more?
ronment) to increase longevity are cheaper.
(f ) Cost of pollution = costs to control pollution + loss from damages. i. May have have opposite trends. Minimum at intersection. A. If minimum cost results in too much pollution, then reducing pollution beyond this point may be considerably more expensive. ii. Total cost may stabilize or decline as pollution control becomes more e cient and external costs decline. iii. Estimated cost of pollution control per family is $3060. 2.
Externalities, or indirect costs are eects not normally accounted for in cost-bene t analyses and are often not recognized as a cost or a bene t. (a) Knowing
true cost
is necessary for rational consumer choice.
(b) Clean air and water and traded largely as if they cost nothing. (c) Dollar value can sometimes be determined: water by ow and storage
Now standard procedure.
in rivers and lakes; forest by inventory of trees and yield; mineral by estimated reserves.
(d) Who should pay? Polluters (then pass costs to consumers) or tax? Consensus that polluter pays approach oers stronger incentives.
51
(e)
Public service functions
have tremendous economic eects. We only
recognize them when we begin to lose one.
What may previously
have been an externality may now become a direct cost.
Natural capital Landscape aesthetics i.
(f )
estimated $3$33
trillion/year.
is di cult to quantize because of dierent pref-
erences.
i. Some say, coherence, complexity, mystery. ii. Others, unity, vividness, variety.
but
(g) Value of the future: pro t in future,
economically, pro t now is worth more than
humans tend to think about the future.
i. Many believe we have obligation to future generations to not damage environment. ii. Spending on environment can be viewed as diverting funds from other productive investments (which may bene t future generations).
Implication: protecting environment is taking from today's poor to give to tomorrow's future. How do you know which sacri ces are important for future?
iii. As wealth increases, so does value placed on environment.
iv. Future value depends of future consumers' view of consumption.
v. If future value is greater than present value, eventually future value will be in nite. That's not possible.
Rule of thumb: do not throw away something that cannot be replaced if you are unsure of future value Marginal costs Often increases exponentially. vi.
(precautionary principle).
3.
is the cost for one additional unit.
4. Empirically, individual transferable quotas have been most eective.
value
5. New York Catskill Mountains case shows that it doesn't take much capital to get people to act because they
7
a clean environment.
Global Change
7.1
Stratospheric Ozone
1. 90% in stratosphere1540km. 2.
Blocks 99% of UV. (a)
UVC
is shortest
λ.
Decomposes O → 2O, then not aected by ozone layer. 2
O
+
O2
→
O3 .
Negligible amounts reach surface (b)
UVA is longest λ and is
52
Some damage.
(c) 3.
UVB is energetic; O3 is only gas known to absorb it.
Dobson unit (DU) = 1 ppb O3 .
4. Hypothesis:
CFCs emitted in lower atmosphere are extremely stable
unreactive, 100 year residence time. (Soils remove an unknown amount,
catalytic chain reaction:
though). Eventually disperse to upper atmosphere. UV decomposes CFC, releasing Cl, which reacts with O3 in a (a) Cl
+ O3 → ClO + O2
(b) ClO
+ O → Cl + O2
(c) Estimated each Cl destroy 100,000 O3 . (d) May be interrupted removed up to 200 times, but UV may decompose Cl compound again at any time:
+ NO2 → ClONO2 Cl + CH4 → HCl (end for
i. ClO ii.
most Cl).
5. CFCs used in aerosol (not problem anymore), coolant (growing problem in developing countries), Styrofoam production. 6. Many solvent contain Cl and react similarly, as does halon (Br).
at equator, but circulates to poles.
7. Naturally, ozone highest at poles and lowest at equator.
8.
Polar stratospheric clouds are observed at 20km. (a) Form during polar winter:
polar vortex.
Mainly produced
Glow.
Antarctic air mass isolated and circles
about pole
(b) Vortex cools, condenses, descends (no sun to warm up). (c) Type I (190195 K): H2 SO4 particles freeze; seed for HNO3 . (d) Type II (< 190 K): water vapor condenses around Type I particles. Mother-of-pearl color.
70% O in weeks.
(e) HNO3 settle out.
3
Cl sink ClONO cannot be formed. Can destroy can dissipate southwards. 2
(f ) Arctic clouds are not as severe, but ClO
9. Tropical, mid-latitude depletion also hypothesized.
Polar stratospheric
clouds migrate; volcanic explosions (SO2 may gentrify). 10. Eects (a)
Reduce ocean productivity:
Antarctic waters decreased primary pro-
ductivity 612% associated with ozone depletion. i. Plankton are CO2 sink
→ 53
exacerbate global warming.
(b) (c)
Disrupt food production Cancer increase Reduce immune function. .
predicted to
until 2060 when ozone layer begins to
recover. (d)
(e) Cataracts. 11. Strategies for reducing ozone depletion (a) Estimated to return to pre-1980 by 2050. Already growth reduced. (b)
Recover
discarded CFCs. 1.2 kg CFC per refrigerator (50 M world-
wide). (c)
Hydro urocarbons:
F reacts similarly to Cl, but 1,000 less e -
cient. Possible to make it not deplete. (d)
Hydrochloro urocarbons can be broken down in lower atmosphere. But if it gets into upper atmosphere, still deplete. Transition; phase out 2030.
12. Relevant laws and treaties (a)
1987 Montreal Protocol27 original, 119 later. i. Reduce CFCs to 50% of 1986 levels. Eliminate by 1999. ii. Developed stopped by 1995; deadline for developing, 2005. iii.
China, India
are not parties.
iv. Requires technology and money for developing countries. v. Black market for CFCs. (b) 1990 London (c) 1992 Copenhagen
7.2 1.
Global Warming
Climate change earth by several
◦
refers to uctuation of annual mean temperature of
C over the past million years.
(a) Temperatures dropped in 1940 but began dramatically increasing starting in 1970s. (b) Milankovitch cycles:
earth's unstable orbit produces 100,000 year
Insu cientseen
cycles, which correlates with major (inter)glacial periods. 40,000 and
as one mechanism among many.
20,000 year changes are result of earth's wobble.
◦
◦
2. Mean surface temperature expected to increase by 1.5 C to 4.5 C by 2100. 3. Surface temperature determine by:
54
(a) Sunlight received and re ected. (b) Heat re ected by atmosphere. (c) Evaporation and condensation of water vapor. 4.
Greenhouse gases re-emits radiation to earth's surface, warming earth. (a) Water vapor responsible for 85% and water aerosol 12%. (b)
Atmospheric window
is the 812
house gases do not absorb well.
◦
But CFCs do!
µm wavelength where natural green-
(c) Lower atmosphere kept 33 C warmer than otherwise and moderate day/night temperature
∆.
(d) CO2 : 5060% of anthropogenic greenhouse eect. i. Exponential growth for 150 years; r = 0.5% per year. ii. By 2050,
1.5×
pre-industrial level.
(e) CH4 1220%; more than doubled in past 200 years. Human sources: land lls, burning biomass, coal and natural gas, agriculture:
rice
(anaerobes release CH4 ,), raising cattle. i.
Naturally,
methane releases may have ended glacial periods and
quickly increased temperatures. As ocean levels dropped, so did pressure on methane hydrates, causing them to be released into the atmosphere. Waters also warmed at the beginning of interglacial periods, further favoring release of methane. (f ) CFCs: inert compounds used at aerosol propellants up to 1978 in U.S. Tremendously more potent than CO2 . (g) N2 O 5%. Fertilizer application and fossil fuels. Long residence time in atmosphere. 5.
Forcing is any process that changes global temperatures.
6. Hypothesized negative feedback: (a) Global warming increases algae, which consume CO2 . (b) Greater [CO2 ] stimulates forest growth, removing CO2 . (c) Polar regions receive more precipitation from warmer air carrying more moisture; deposited snow re ects heat. (d) Warmer temperature evaporates more water from oceans, forming more clouds, which re ect heat. 7. Hypothesized positive feedback:
ing.
(a) Increase oceanic evaporation increases water vapor
55
increase warm-
(b) Melting of permafrost releases methane. (c) Reducing
summer snowpack
reduces re ection.
(d) People use additional air conditioning, burning more fossil fuels. 8. Both negative and positive occur spontaneously, but evidence points to positive being favored. Role of water vapor is critical and not well understood. 9.
Global dimming is the reduction of solar radiation by re ection o par-
seeds for clouds
ticles and their interaction with water vapor. SO2 and volcanic aerosols oset some global greenhouse eect because they at as
. In
some areas pollutants oset 50% of expected warming due to greenhouse gases. 10. Potential consequences: (a)
Polar ampli cation is positive feedback of ice melting, thus re ecting less heat.
(b) Climate change could damage agricultural productivity because optimal climate is not longer paired with optimal soil.
less
i. Runo may be much faster because snow pack is reduced, leading to
runo for more downstream regions.
ii. Could increase occurrence or magnitude of violent storms be-
has
cause warmer ocean water puts more energy into storms. Past hurricanes show average magnitude rence has not).
increased (but occur-
thermal expansion of water, melting of glacial ice.
(c) Rising sea levelshalf the people on earth live near the coast! Caused by (1)
(2)
i. Already 12mm/yr. Estimated 4555
cm by 2100.
ii. Increase coastal erosion, loss of wetlands, saltwater intrusion. (d) Glaciers melt, but Antarctic ice cap grows.
Consistent with models.
(e) Changes in biosphere: evidence of many animals adapting. i. Some species cannot adapt quickly enough, particular plants, ii. Wild relatives of crops used for hybridization may die. iii.
↑
range of mosquitoes carrying
malaria, dengue fever.
iv. Possibly responsible for spread of West Nile Virus to New York City. 11. Simply learning to live with global warming may not be the best idea because the rapid rise may bring many nasty surprises.
◦
If reduced to
below 2.0 C over the next century, then very likely to be able to adapt. 12. Reducing climate change:
56
(a) California (itself 12th largest greenhouse gasser) passed legislation to reduce emissions by 25% by 2020. (b) Conserve; use nuclear and renewables; use natural gas instead of other fuels. (c) Minimize burning of forests;
reforest.
(d) Geologic sequestration: capture CO2 and inject into reservoirs. Depleted oil elds or saltwater aquifer. Need to sequester 2 GtC/yr to be eective. i. Norway sequester CO2 from natural gas production facility under natural gas eld in North Sea. Expensive, but so is paying carbon tax. 13. Laws and Treaties (a) 1987
Montreal Protocol signed by 24 states to reduce and eliminate
CFC use and develop alternatives. Nearly phased out by 2000.
7.3
Loss of Biodiversity
7.3.1 Habitat loss; overuse; pollution; introduced species; endangered and extinct species
introduced to dierent biotic provinces (regardless of biome) likely to cause trouble
1. Species
because the introduced and local species have not evolved
with each other. (a) (b)
Ubiquitous species can be found anywhere. Cosmopolitan species can be found almost anywhere within suitable conditions.
(c) (d)
Endemic species can be found naturally in only one place. Exotic species are species introduced into an area where it has not evolved.
ened Species
2. International Union for the Conservation of Nature's
Red List of Threat-
(a) 20% known species of mammals, 12% birds, 4% reptiles, 31% amphibian, 3% sh, 3% vascular plants. 3.
Endangered species means any species which is in danger of extinction throughout all or a signi cant portion of its range [except insect pests].
4.
Threatened species
means any species which is likely to become an
endangered species within the foreseeable future throughout all or a signi cant portion of its range.
57
5. Causes of Extinction (a) Population risk: random variations in birth and death rates result in many individuals unable to nd mates. (b) Environmental risk:
non-catastrophic changes kill species.
Some-
times can be very isolated, for example, speci c pollinator/ ower relationship: if plants die, so do pollinators. (c) Natural catastrophe. (d) Genetic risk:
not
(
including environmental damage) genetic drift,
widespread mutation.
7.3.2 Maintenance Through Conservation 1. Goals: two approaches: (a) To some pretechnological number. Complex, inaccurate. (b) Seek some determinable number: minimum viable, optimal population, etc. i.
Minimal viable population is smallest
estimated population
to maintain itself and its genetic variability inde nitely. ii.
Optimum sustainable population
is the
largest
estimated
population to sustain itself without detriment to ecosystem. 2. Sometimes protection works too well:
sea lions, mountain lions
have be-
come problems for human life and property.
3. Spatial relationshipslooking at each specie's habitatcan allow for preservation of certain species without compromising other species.
7.3.3 Laws and Treaties 1. Endangered Species (a) 1973
U.S. Endangered Species Act listed endangered, threatened
species and was the most wide-ranging piece of environmental legislation in the 1970s. As of 2007, 41 species have been de-listed
58
ence: Earth as a Living Planet
This guide follows the College Board's Topic Outline.
Environmental Sci-
by Botkin and Keller, 6th edition, was the main
source for these notes.
Contents 1 Earth Systems and Resources
2
1.1
Earth Science Concepts
. . . . . . . . . . . . . . . . . . . . . . .
1.2
The Atmosphere
3
. . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.3
Global Water Resources and Use
. . . . . . . . . . . . . . . . . .
5
1.4
Soil and Soil Dynamics . . . . . . . . . . . . . . . . . . . . . . . .
7
2 The Living World
8
2.1
Ecosystem Structure . . . . . . . . . . . . . . . . . . . . . . . . .
2.2
Energy Flow
2.3
Ecosystem Diversity
2.4
Natural Ecosystem Change
2.5
Natural Biogeochemical Cycles
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Populations
8 11 11 12 13
14
3.1
Population Biology Concepts
. . . . . . . . . . . . . . . . . . . .
14
3.2
Human Population . . . . . . . . . . . . . . . . . . . . . . . . . .
15
3.2.1
Human Population Dynamics . . . . . . . . . . . . . . . .
15
3.2.2
Population Size . . . . . . . . . . . . . . . . . . . . . . . .
15
3.2.3
Impacts of Population Growth
16
. . . . . . . . . . . . . . .
4 Land and Water Use 4.1
Agriculture
16
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1
Feeding a Growing Population
4.1.2
. . . . . . . . . . . . . . .
16 16
Controlling Pests . . . . . . . . . . . . . . . . . . . . . . .
18
4.2
Forestry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
4.3
Rangelands
4.4
Other Land Uses
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
. . . . . . . . . . . . . . . . . . . . . . . . . . .
19
4.4.1
Urban Land Development . . . . . . . . . . . . . . . . . .
19
4.4.2
Transportation Infrastructure . . . . . . . . . . . . . . . .
21
1
4.4.3
Public and Federal Lands
. . . . . . . . . . . . . . . . . .
22
4.4.4
Land Conservation Options . . . . . . . . . . . . . . . . .
22
4.4.5
Sustainable Land-Use Strategies
22
. . . . . . . . . . . . . .
4.5
Mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
4.6
Fishing
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25
4.7
Global Economics . . . . . . . . . . . . . . . . . . . . . . . . . . .
26
5 Energy Resources and Consumption
26
5.1
Energy Concepts
. . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2
Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . .
27
5.2.1
History
27
5.2.2
Present Global Energy Use
. . . . . . . . . . . . . . . . .
27
5.2.3
Future Energy Needs . . . . . . . . . . . . . . . . . . . . .
28
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3
Fossil Fuel Resources and Use . . . . . . . . . . . . . . . . . . . .
28
5.4
Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
5.5
Hydroelectric Power
. . . . . . . . . . . . . . . . . . . . . . . . .
32
5.6
Energy Conservation . . . . . . . . . . . . . . . . . . . . . . . . .
33
5.7
Renewable Energy
34
. . . . . . . . . . . . . . . . . . . . . . . . . .
6 Pollution 6.1
6.2
6.3
36
Pollution Types . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
6.1.1
Air Pollution
36
6.1.2
Noise Pollution . . . . . . . . . . . . . . . . . . . . . . . .
41
6.1.3
Water Pollution . . . . . . . . . . . . . . . . . . . . . . . .
42
6.1.4
Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . .
Impacts on the Environment and Human Health
45
. . . . . . . . .
49
6.2.1
Hazards to Human Health . . . . . . . . . . . . . . . . . .
49
6.2.2
Hazardous Chemicals in the Environment
Economic Impacts
. . . . . . . . .
50
. . . . . . . . . . . . . . . . . . . . . . . . . .
51
7 Global Change
52
7.1
Stratospheric Ozone
. . . . . . . . . . . . . . . . . . . . . . . . .
7.2
Global Warming
52
. . . . . . . . . . . . . . . . . . . . . . . . . . .
54
7.3
Loss of Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . .
57
7.3.1
Habitat loss; overuse; pollution; introduced species; en-
7.3.2
Maintenance Through Conservation
7.3.3
Laws and Treaties
dangered and extinct species
1
26
. . . . . . . . . . . . . . . .
57
. . . . . . . . . . . .
58
. . . . . . . . . . . . . . . . . . . . . .
58
Earth Systems and Resources 1. Average Residence Time (ART): ratio of size of reservoir to rate of transfer through reservoir:
ART = S/F Where
S
is size of reservoir and
F
2
is rate of transfer.
1.1 1.
Earth Science Concepts
Lithosphere is crust.
2. Geological cycles include (a) Tectonic: can create ecological islands. i. Divergent plates boundaries occur at a spreading ocean ridge (sea oor spreading). ii. Convergent plate boundaries occur when plates collide. A.
Subduction
is the heavy ocean rock diving beneath the light
continental rock. May produce coastal mountain ranges (Andes). B. Continental collisions may produce continental mountains. iii. Transform fault boundaries occur when one plate slides past another. (b) Hydrologic (c) Rock (d) Biogeochemical 3.
Earthquake occurs when tectonic plates under pressure rupture, releasing huge amounts of energy (more than a large nuclear explosion), usually at 1015 km along faults. (a) Fault planes bar groundwater. Rocks crushed, then altered into clay. Water forced to surface, creating vital habitats, especially where arid.
4.
Volcanic eruption
occurs when magma rises to the surface.
or
Energy
released varies broadly. Volcanoes occur along tectonic plate boundaries, where active melting of rocks favors extrusion of magma, parts of plates where local hot spots heat and melt rock. 5.
along central
Tsunami is a series of large waves produced after the vertical disturbance of ocean. 80% are produced by earthquakes. They travel at jet aircraft speeds but slow and get taller as they approach the surface.
1.2
The Atmosphere
1. Composition is 78% N2 , 21% O2 , 0.9% Ar, 0.03% CO2 . 2. Structure in order is: troposphere, tropopause (condensation traps water vapor), stratosphere (O3 ), stratopause, mesosphere, mesopause, thermosphere. 3. 25% of incoming solar radiation re ected straight into space, 25% absorbed by atmosphere.
3
4. Atmospheric circulation: (1) rotation and (2) dierential heating.
◦
(a) Low pressure at equator, 5060 .
◦
(b) High pressure from descending air 2530
→
arid. Sandwiched be-
tween two zones of high precipitation (low pressure).
(c) (d)
Easterlies Trade winds
at poles and
Westerlies
from 3060
◦
◦
meet at 60 .
blow to west; meet at equator, where
(regions with little air movement). 5.
doldrums
occur
El Niño events (also ENSO) occur every 27 years, lasting for 11 12 years. East-west trade winds weaken and eastern Paci c waters warm
→ tropical
rainfall shifts from Indonesia to South America. Floods in Peru; droughts
Natural.
and res in Indonesia and Australia. Upwelling at South American coastline is suppressed. (a) 6.
La Niña opposite; exaggerate normal patterns.
Tornadoes are funnel-shaped clouds of rapidly rotating wind.
They form
out of severe thunderstorms that occur when a cold air mass collides with a warm one. Water vapor in the warm part is forced upwards, cools, then precipitates. 7.
Hurricanes are tropical storm with circulating winds of at least 120 km/h that moves across tropical ocean.
tropical depression
(a) An organized mass of thunderstorms with low pressure begin to circulate, forming a
.
(b) Huge amounts of energy are stored as
latent heat
Condensation releases this energy, warming air.
vaporization.
As this air rises,
more water is drawn, increasing the size of the hurricane. (c) Rain bands form as the warm air rises.
warm water increases intensity.
(d) Nearing landfall, hurricanes may slow down in shallower water, but
(e)
Storm surges
occur when the hurricane winds push water towards
the coast, which may rise to be over 10 m and may be exacerbated by high tide. 8.
Heat waves
most deadly
are extended periods of unusually hot weather caused by
heating of atmosphere and moving of air masses. of all weather-related hazards.
They are considered
Global warming may have
increased their severity and incidence.
9.
Droughts are long-term (months to years) periods of usually dry weather that are related to natural cycles of wet and dry years, which in turn are not well understood.
4
10. Coriolis eect is apparent de ection of moving objects when viewed from a rotating frame of reference. (a) Free objects on surface appear to go right in Northern hemisphere and left in southern. (b) Air and water ows
right
in north,
left
in south.
(c) Responsible for cyclones.
1.3 1.
Global Water Resources and Use
Groundwater is water below the water table, which is saturated. (a) Surface water enters at (b) (c)
Vadose zone Aquifer Cone of depression
recharge
and exit at
discharge
20%.
zones.
is unsaturated area above water table where water moves.
is underground zone where water can be extracted at a useful
rate. Gravel or sand. (d) (e)
occurs where well is: water level is locally lower.
E uent streams maintain ow during dry weather by groundwater seepage (they are below water table).
Most perennial streams are
e uent. (f )
In uent
(g)
Reaches
ephemeral stream.
streams are entirely above water table; ows only in re-
sponse to precipitation. Called
are sections of a stream that may be e uent, in uent, or
intermediate. (h) Though reserves are huge (conservatively 200 years of Mississippi ow), pumping costs limit amount that can be economically recovered. i.
Overdraft occurs when withdrawal rate > natural in ow.
ii. Essentially nonrenewable because it can
→
damage ecosystems,
land subsidence. iii. TexasOklahomaHigh Plains area (Ogallala aquifer): prime example. Used 20 times faster than being renewed. 2. Surface and ground-water related: (a) Use groundwater
crease
→
(b) Divert surface water
decrease surface levels
→
decrease ground levels and quality OR
pollutants if divert to recharge zone.
too.
3. Ocean circulation
5
in-
Pollution interrelated
◦
(a) Oceanic conveyor belt:
(Gulf Stream) water 1213 C arrives at
Greenland. Cooled and becomes more saline in North America (2
◦
4 C), sinks to bottom.
Flows south, east, north into Paci c.
Up-
◦
welling starts warm shallow current. Keeps N. Europe 510 C cooler. (b) Forces include: rotation, gravity of moon.
wind
, temperature and salinity dierences,
4. Only 50% of precipitation is considered available 95% of the time. 5.
Desalination will remain expensive because it has place value:
it is very
expensive to transport water.
(a) Discharge of brine waste may damage ecosystems. 6. Stream usage (a) (b) (c)
O-stream use is removal and return (power plant). Consumptive use is not returned (drinking, irrigation). In-stream use uses the stream itself or modi es it. Each use requires dierent rates of discharge that cannot be met simultaneously. i. Hydroelectric power prefers large uctuations. ii. Fish and wildlife prefer larger ows in spring and summer, as does recreation. iii. Navigation prefers constant ow.
(d) Aral Sea demonstrates that removing too much water is deleterious to ecosystems. The sea area has been reduced by 40%, volume by 50%. Economically important sh are dying, and shing towns bordering the sea are now inland. Restoration just beginning. 7. Industrial and domestic use (U.S.) (a) Agriculture, industry began leveling o around 1980. Suggests conservation working. (b) Water for public supply continue to increase. 8. Conservation expects to to increase.
reduce total withdrawals
yet allow consumption
(a) Agriculture can reduce 2030%: i. Don't subsidize water. ii. Integrate surface and groundwater use: use store surface water (in ltration pool or injection well) when abundant, groundwater when not. iii. Use high-tech to maximize delivery e ciency.
Irrigate when
evaporation is minimal. Use improved irrigation (drip).
6
iv. Improve soil:
↑
in ltration,
↓
runo.
v. Use crops that require less water or are more salt-tolerant. (b) Domestic use is only 10%, but
concentrated in urban.
i. Don't do lawns in semi-arid regions! ii. Use e cient bathroom xtures1.6 gpf instead of 5.0. iii. Utilities should price water based on non-linear curve to encourage consumption. (c) Industry can reduce electricity generating water 2530% by using low water/no water evaporation tower, in-plant water reuse. (d)
Perception
impacts people's attitudes toward water conservation.
i. Tucson: people think it's desert; conserve. Water expensive. For example, price per unit increases if usage increases past baseline. ii. Phoenix: water cheap; people don't bother conserving.
need emergency plans to minimize hardship:
9. In wet years, plenty of surface water, and groundwater is recharged. Dry years,
(a) Plan to drill and connect wells for deep groundwater, even though too expensive to normally use. (b) Prepare to treat waste water for reuse when needed.
1.4
Soil and Soil Dynamics
1. Rock Cycle (a) (b)
Igneous rock forms from lava. Cracking, weathering split. Sedimentary rock forms from pressure of lots of sediment: sition + lithi cation.
depo-
i. Weathered rock. ii. Carbon sediments by life. (c)
Metamorphic rock forms from sedimentary rocks transformed through heat, pressure, or chemicals. May be uplifted into open.
2.
Soils
are
earth materials horizons:
modi ed by physical, geological, and biological
processes into
(a) O: black organic layer. Decomposing stu. (b) White powderbleached of organic compounds. (c) A: mineral and organic. Brown/light-black. Minerals leach here. (d) E: lighter-colored because clay, minerals leached. (e) B: zone of accumulation (of leached stu above).
7
(f ) C: parent materialpartially weathered bedrock. 3. Rainwater (pH
= 5.5)
leaches minerals.
4. Soil fertility (a) Young rocks fertile: corn belt (recent glacier). (b) Semiarid regions fertile; need water. (c) Humid areas/tropics infertile: leaching due to rainfall. Most nutrients in vegetation. Succession di cult if forest cleared. 5. Semiarid soils expand and contract with water. Damage buildings. 6.
Clay
hold water.
Sand
allows water to drain. Combination retains water
enough for growth but still drains. Coarser soils more easily eroded.
7. 8.
Loams
are best soils; have all particle sizes.
Landslides
occur when driving forces (gravity) that tend to move soil
and things in the soil down a slope overcome resisting forces that hold the ground in place (interlocking grains, natural cementing, plant roots,
reduces
strength of materials on slope). Addition of water or removal of vegetation resisting forces.
Some landslides are reactivations of prehistoric
slides; these areas repeatedly experience landslides (see La Conchita). (a) In mountains, create lakes by damming valleys. 9.
Floodplain is river and atland draining into it.
Naturally, oods annu-
ally. (a) Deposit nutrients on oodplain. (b) Wetlands provide habitat. (c) Floodplain is distinct from adjacent environments
2
→
diversity.
The Living World
2.1 1.
Ecosystem Structure
Ecosystem is the simplest entity that can sustain life.
Support chemical
cycling and energy ow. 2.
Habitat is where a species lives; niche is what it does. (a) Conservation requires paying attention to both, as well as
symbionts.
obligate
(b) Predation can increase diversity by mitigating competitive exclusion.
8
3.
Watershed de nition of ecosystem:
delineated by land that drains into
same stream. 4.
Community-level interactions occur when a species indirectly
aects
another by aecting intermediary species or the environment. (a) Sea otters (b) 5.
eat key urchins →
allow kelp to grow.
Keystone species are necessary for the basic nature of a community.
Biotic provinces are geographic regions (including ocean) inhabited by characteristic set of taxa sharing
common evolutionary history
and repro-
ductively isolated from other provinces. (a) Formed by continental drift.
(b) Safer to introduce species within its biotic province. 6.
Biomes are de ned by climate, which selects for common traits (convergent evolution).
7.
Island biogeography:
smaller and more distant islands have fewer species.
Migration and evolution supply new species. (a)
Ecological island is a separated small habitat:
park, oceanic island
(over shing), patches of uncut forest. 8. Major biomes
(a) Tundragrasses, mosses, lichens; dwarf shrubs. i. Arctic tundra has large animals; (b) Taiga/Boreal Forestconifers.
alpine tundra
does not.
Low biodiversity; commercially im-
portant. i.
Northern America and Eurasia.
ii. Moose, deer, wolves, bears, foxes, squirrels, rabbits. iii. Water foul, owls, eagles. iv. Disturbances, esp. re, frequent. (c) Temperate Deciduoushardwood trees. i.
China, Japan, W. Europe, U.S., urbanized Canada.
ii. Most changed by humans. iii. Small mammals, birds, insects. (d) Temperate Rain Forestsconifers. i.
North America, New Zealand.
ii. Rare. Conifers because they photosynthesize during non-freezing winter.
9
(e) Temperate Woodlandssmall trees, open. i.
Drier than deciduous forest, same temperature.
ii. Fire regular. iii. Forest plantations in this biome.
chaparral) shrubs.
(f ) Temperate Shrublands ( i.
Mediterranean, SoCal, Chile, S. Africa. Sage
ii. Most attractive to people; little native left. iii.
plant. Aromatic.
iv. Reptiles, small mammals. v. Fire regular. (g) Temperate Grasslandsmidpoint between forest and desert. i.
N. American prairie, steppes of Eurasia, plains of Africa, pampas of South America.
ii. Rich organic soil. iii. Most important agriculturally. iv. Largest abundance and diversity of large mammals. v. Fire and grazing maintain identity as grassland. (h) Tropical Rain Forests i. Soil low in nutrients; plants adapted to rapidly uptake. ii. Found in very remote regions. (i) Tropical Seasonal Forests and Savannas i.
India, Southeast Asia, Africa, South/Central America.
ii. High temperature, variable rainfall. iii. Fire and grazing maintain identity. (j) Desertsrainfall < 50 cm/year. (k) Wetlandssoil has little oxygen; slow decay. Flooded and saturated at least several days a year. i. Bogs have water entry but no outlet. ii. Swamps and marshes have entry and exit. iii. Produce fossil fuels. iv. Bacteria produce CH4 , H2 S. v. Saltwater marsh: breeding ground for oceanic animals. vi. Services: A. Reservoir. Hold high ow; release to augment low ow. B. Important areas of groundwater recharge or discharge. C. 45% endangered animals, 26% endangered birds depends on wetlands. D. Natural lters: plants trap sediment and toxin.
10
E. Important production and storage of biomass, rich soil. vii. Perhaps 90% of freshwater wetlands lost. viii. Urbanization usually on coast, riverbank, or other place favorable to wetlands. ix. Most wetlands now privately owned. (l) Freshwaters i.
Estuaries
mouth of riversrich in nutrients.
ii. Important source of water for animals, civilization. (m) Intertidalmajor economic resource, algae (including kelp). i. Easily polluted; manipulated by people, recreation, urbanization. ii. Extreme changes are part of life. (n) Open Ocean
pelagic region.
Low in N, P.
(o) Benthosdeeps. Food is dead stu that falls from above. Too dark. (p) Upwellingsdeep ocean water rich in nutrients. Flows bring nutrients to surface. West coast of America, Africa, ice caps. Sometimes wind pushes coastal waters away, pulling deep water up. (q) Hydrothermal Ventschemosynthesis. Unusual life-forms. High pressure, extremely variable temperature.
2.2
Energy Flow
1. Photosynthesis and cell respiration 2.
Biological production is capture of energy into organic molecules; net production is the biomass/energy
stored
, not used.
3. Food webs and trophic levels (a) Species that feed on multiple levels classi ed by the highest. (b) Naturally
1% energy transferred between trophic levels.
(c) Many freshwater ecosystems depend on detritus, as benthic. 4. Herbivores can eat stu humans can't eat (algae)
or
graze without damag-
ing land. Vegetarianism for everybody does not maximize food resources.
2.3 1.
Ecosystem Diversity
Biodiversity is expressed as number of species in an area, but popular usage varies. (a) About 1.4M named species, mostly insects and plants and mostly in tropics.
11
(b)
Genetic diversity is total number of genetic characteristics of group (species, subspecies, arbitrary, etc.)
(c) (d)
2.
2.4
Habitat diversity is dierent kinds of habitats in given area. Species diversity i. Species richness is total number, ii. Species evenness is relative abundance, iii. Species dominance is the most abundant species.
Ecosystem services Natural Ecosystem Change
r
1. Ecological Succession: early-succession species are adapted to harsh en-
K
vironment with plentiful resources ( -selected); later species are more resource-e cient but cannot withstand harsh environment (
-selected).
(a) Dune Successionconstantly formed and destroyed along sandy shores. i. Dune grass forms runners underground. Stabilize other seeds. ii. Small, hardy plants grow. iii. Eventually, trees. (b) Bog Successionsedge (grass-like herbs) put oating runners. i. Wind blows stu onto sedge mat; soil forms. ii. Plants grow on sedge; sedge thickens. Really oating mat. iii. Sediments deposit. iv. Eventually, wetland forest. (c) Old-Field Successionsmall, hardy plants, eventually trees. (d) Biodiversity, biomass increase (e) Gross production
↑;
peaks during middle succession.
net production
↓.
(f ) Vegetation retards erosion. (g) Ecosystem eventually runs out of biomass. (h) Species-interaction i. ii.
Facilitationone species prepares way for another (bog). Interferenceearly plants prevent entrance of later (dense grasses prevent other seeds from reaching ground).
iii.
Life history dierenceslowly-propagating
species reaches
succession site later than do quickly-propagating species. iv.
Chronic patchinessenvironment
dominates and succession
never occurs. 2.
Wild res occur when vegetation cannot be decomposed quickly enough to balance the carbon cycle, resulting in an accumulation of fuel.
12
2.5
Natural Biogeochemical Cycles
Chemicals with a gas phase use atmosphere as reservoir and cycle quickly; chemicals lacking gas phase often exist in unusable forms and are often insoluble in water and cycle slowly. 1. Carbon (a) (b) (c) (d)
Reservoirs: Assimilation: Cycling: Loss
atmosphere, ocean, rocks, soil, fossil fuels. photosynthesis.
predation, weathering and erosion.
: respiration, decomposition (release CO2 ), forest res, burning
fossil fuels, volcanic eruption. Fossil fuel formation where too cold or not enough to decompose. (e)
Missing carbon sinkabout 3 GtC (billion metric tons of C) unaccounted for. i. Sink changes size. ii. Believe sink is terrestrial.
(f ) Carbon-silicate cycle: H2 CO3
+ XSiOn + CaCO3 → Ca2+ + HCO− 3 + SiO2
These minerals precipitate and are extracted by marine organisms and form sediment in the ocean. Metamorphosis in subduction zones releases CO2 and reforms silica products. 2. Nitrogen (a) (b) (c)
Reservoirs: Assimilation: Cycling:
air, soil, ocean. nitrogen xation, lightning, industry (50%).
internal, erosion and runo, sea spray. Usually plants rst.
Ruminants have nitrogen- xing bacteria in their stomachs that prove 50% of N. (d)
Loss:
de-nitri cation, marine sedimentation.
3. Phosphorus (a) (b) (c)
Reservoir: Assimilation: Cycling:
phosphates of Ca, K, Mg, Fe. uptake by plants, algae, some bacteria.
to ocean (in soluble form or suspension), ocean-feeding birds
(guano deposits), upwellings (winds push surface water away from land, exposing deeper, nutrient-rich water), uplifting of sedimentary rock. (d)
Loss:
ocean sedimentation.
13
4. Sulfur (a) (b) (c) (d) (e)
Reservoirs Available reservoirs: Assimilation: Cycling: Loss
: rock, soil. air, below ground.
root uptake, gaseous uptake.
litter fall (to ground), root leakage.
: to streams, to atmosphere.
5. Water (a) Local land-use changes can change precipitation. (b)
Drainage basin is land that drains into a particular stream/river.
6. Conservation of matter
3
Populations
3.1
Population Biology Concepts
1. Logistic growth
unrealistic
: relies on
(a) Constant environment (b) Constant
K
(c) Homogeneous population (each has same impact) 2.
K can only be estimated if logistic curve has reached growth rate slows).
in ection point
(when
(a) Estimates before in ection point undershoot. (b)
Maximum sustainable yield 1 2 K , but unrealistic.
20th century.
occurs at
Mis-estimates led to over-harvest in
is the highest rate of growth and
3. Doubling time (reverse of half-life):
Td = where
k
is the constant in
ln 2 0.7 ≈ k k
N = N0 ekt .
14
3.2
Human Population
3.2.1 Human Population Dynamics 1. History (a) Hunter-gatherer; few million. 0.00011%. (b) Agriculture; 0.03% i. A.D. 1: 5M ii. 1600 500M (c) Industrial; 0.1% i. 1800: 900M ii. Doubled twice (3B) by 1960 (d) Modern; 1.2% (Total Fertility Rate = 2.5) 2. 95% of current growth from developing countries. 3. Demographic transition: (a) Lower death rate (medicine against acute illnesses) (b) Then, lower birth rate (education, wealth, social change) (c) Possibly repeat (medicine against chronic illnesses) 4. Age-structure diagrams show past, present, and future.
3.2.2 Population Size 1. Sustainability = zero population growth. 2.
↑
Age of rst childbearing.
(a) 4050% of needed fertility reduction. (b) Sri Lanka. 3. Birth control. (a) Breastfeeding. (b) 46M abortions yearly. 4. National policies: information and access to birth control, explain problems of overpopulation, explain bene ts of fewer children, instituted rewards and punishments. (a) India (1952). (b) Ghana, Malaysia, Pakistan, Singapore, Philippines use tax disincentives.
15
(c) Tanzania restrict maternity leave. (d) Singapore: bigger families more crowded, admission priority for small family. (e) Sri Lanka, Bangladesh, India: government pays you for sterilization. (f ) China i. 1978: goal ZPG by 2000. ii. Achieved 1.0%.
3.2.3 Impacts of Population Growth 1. Ultimate cause of current unsustainability and current environmental problems. 2. Resources and food
per capita peaked in 1960s1970s.
3. Economics (a) Positive feedback in poor countries: low income
→
more children
→
keeps per-capita income low.
4
Land and Water Use
4.1
Agriculture
4.1.1 Feeding a Growing Population 1. Undernourishment: insu cient calories. (a) Marasmuslack of protein and calories. i. Kwashiorkorlack of protein
→
failed neural development.
ii. Chronic hungerunproductive. (b) Malnourishment:
lack of speci c component.
people unproductive.
Long-term.
i. Macronutrients: C, H, N, O, P, S; Ca, Na, K. 2. Types of agriculture (a) (b) (c)
Rangelandfood for grazers/browsers. No plowing. Pastureplanted to provide animal feed. Organic farming i. More like natural ecosystemnot monoculture. ii. Minimize negative impacts. iii. Food does not contain arti cial chemicals.
16
Makes
(d) In
monoculture organic farming
, seed companies predict growing season climates and
likely strains of pests and diseases. If they're wrong, you're screwed. In contrast,
average
plants a mixture of crops or a broad
range of genotypes, resulting in lower risk of very-low-production.
yield but mitigates
Unnatural.
3. Plowing damages soil: succession to dierent climax or much more slowly.
(a) Natural vegetation maintains structure and enriches soil. (b) Plowed land destroys structure and exposes soil; crops remove nutrients; heat decomposes nutrients. (c) Erosion damages water productivity. (d) 1mm soil produced 10 to 40 years. (e) (f ) 4.
Contour plowing is the s0ingle most eective way to reduce erosion. No-till agriculture allow some weeds, leave decaying plants.
Green Revolution is the post-war program that led to crops with higher yields, better disease resistance, or better ability to grow in marginal conditions. (a) Rice hybridization at the International Rice Institute in the Philippines. (b)
Drip irrigation
e cient, but expensive, so not likely used in hungry
places.
5. Genetic engineering and crop production (a) U.S.: 1/3 corn, > 1/2 canola oil, 3/4 soybeans. (b) Hybridization risks: superhybrid can grow where unwanted; superweed had genes transferred to it. (c)
Terminator gene sterilizes seeds.
(d) BT corn produces pesticide in
Prevents GMO spread.
every
cell.
Unknown eect on con-
sumers; toxic pollen can kill monarch butter ies. 6. Key to future food production appears to be increased production per unit area, on increasingly worse land. 7. Global warming
decrease
yield because best soils have best suited climates.
17
4.1.2 Controlling Pests 1.
2 1 3 harvest lost; 10 post-harvest lost. (a) 1050 species of weeds infest each farm.
Devastating: Narrow-spectrum pesticide (b)
2.
cocklebur reduces soybean yield up 60%. targets one organism.
Elusive magic bullet.
(a) Unexpected eects continue to appear. 3. Natural pesticides safe, but not as eective 4.
Biological control uses predators and parasites to control pests. (a)
Bacillus thuringiensis
(BT) infects caterpillars and others.
(b) Parasite wasps (of caterpillars): eective narrow-spectrum. (c) Ladybugs. (d) Sex pheromones to trap or confuse insects. 5.
Integrated pest management uses many techniques to control
rather
than eliminate. (a)
Diminishing returns
as pest removal approaches 100%.
(b) Retaining pest population reduces ecosystem damage.
Physical complexity of habitat reduces pests because it is harder for them to nd food.
(c) Move beyond monoculture.
(d) No/low-till: natural predators of pests accumulate in soil. (e)
4.2
Speci c
application of chemical pesticide.
Forestry
Reduce pressure on other forests.
1. Tree plantations can potentially supply world's timber in 10% of forestland.
2. Forest res (a) Past suppression
→
accumulation of fuel. Now, res are more dam-
aging, and may even burn away organic matter and old trees that normally survive res. 3. Forest management (silviculture) is complex and di cult, but easy to get data (tree rings). (a) Remove poor trees (b) Breed new strains (like crops)
18
(c) Control diseases (usually fungal) and pests.
Little success.
i. Gypsy moth (introduced for silk) defoliate trees. ii. Insects eat leaves, buds, fruits, carry disease. (d) Cutting techniques i.
ii.
Shelterwood-cutting
Always young trees left.
cuts less desirable and dead trees rst.
Seed-tree cutting removes all but a few good, mature ones to promote regeneration.
iii.
Thinning cuts only poor, small trees.
4. National forests compose 11.2% of U.S. area; 12% Costa Rica; depend on amount of forest in country. 5. Clear-cutting is not absolutely bad or good; need to evaluate case-by-case. (a) Level ground, moderate rainfall, clear-cut can regenerate species. 6.
Ecosystem services include retarding erosion, moderating water availability, habitats for endangered species/other wildlife, impacting climate.
4.3 1.
Rangelands
Arid rangeland is easily damaged by grazing; 30% is done there.
2. Cattle trample and erode stream banks and pollute streams. 3.
Overgrazing slows growth, reduces diversity, leads to dominance of un-
desirable plants for grazing. decreases
4. Carrying capacity 5.
with aridity.
Deserti cation is deterioration of dryish land due to climate change and human activity. (a)
Marginal lands
cannot tolerate much human activity. Overstressed.
(b) Poisoned soil (persistent pesticide, . . . ) forces abandonment. (c) Irrigation in arid areas: salt residue accumulates to toxicity.
4.4
Other Land Uses
4.4.1 Urban Land Development 1. 45% live in cities today; 62% by 2025. (a) 75% in developed. (b) 38% is poorer developing.
19
(c) Most estimated to live in country's largest city. 2. Cities, countryside mutually dependent. Many serious environmental problems occur at the interface. 3.
Site is the environmental features of location. (a) Sometimes change: silting harbors destroys economic value.
4.
Situation is placement of city relative to other areas (e.g.
transportation
hub). (a)
Fall line
cities here.
is location of waterfall or rapids on major rivers.
Many
(b) Usually where people would naturally meet: con uence of rivers, river enter lake, next to mineral or spring. 5. Developments that make city seem more independent of nature actually increase dependence. 6. Buildings de ect and channel wind, altering weather patterns. Generally, makes it more di cult to remove pollutants. 7.
Planned development: (a)
Design with nature
fortress city and park city.
attempts to take advantage of features that na-
ture provides instead of destroying nature. (b)
Garden cities are surrounded by greenbelts.
(c) Urban trees face special stress:
soil.
i. Compacted soil. Suer from water extremes.
ii. Air pollution, dust, physical impact
→ ↑
Specially prepare
susceptible to fungal
infection. iii. Must not produce messy leaf, fruit, or owers. iv. Usually, few species used
→
fragile ecosystem.
v. Early succession plants do best. vi. Endangered plants can be planted. Sometimes do well. (d) Habitats for wildlife. Can contribute to conservation. 8. Pests usually are generalists (share people's diet), r-selected. (a) Key to
eliminate habitats.
Don't leave garbage open!
(b) Identify natural t and naturally controlling factors. 9. Adversely aect water cycle.
20
(a) Pavement prevents in ltration. (b) Most cities have one sewer. During storms, runo may exceed treatment capacity, ejecting raw sewage. (c) Evaporation reduced (runo )
→
higher temperature.
(d) Increased particulates
→
(e)
often succeed in controlling runo, recharge
Constructed wetlands
increased rain, clouds, fog.
aquifer, and are cheaper than conventional drainage. 10. Soils lose vegetation 11.
→
lose organic matter, organisms die, compacted.
Urban sprawl is uncontrolled growth, usually of suburbs. (a) Presently, Maryland could urbanize as much land in 25 years as it has in history. (b) Boulder established blue line in 1959no water or sewer beyond. Limited residential and job growth. Economy grew. (c)
However,
neighboring cities grew, and commuting is damaging envi-
ronment. 12.
Made lands are arti cial.
Unnatural.
Unconsolidated
loose ller with-
out rock support. Vulnerable to earthquake.
4.4.2 Transportation Infrastructure 1. Canal have smooth, steep banks, VERY fast water. Drown! (a) Much unforeseen environmental problems: Aswan High Dam + canals
→
snails with schistosomiasis. Nile oodwaters used to ush them.
(b) In some parts, almost everybody is aected by schistosomiasis. 2.
Channelization is modi cation of existing streams (straightening, widening, lining, deepening) to control oods, improve drainage, control erosion, improve navigation. (a) Fast ow lose sh habitats.
Increased temperature, since trees on
banks cut. (b) Downstream ooding worse, since channelized section carries more water than supposed to. (c) Damage wetlands; depresses water table. (d)
Not always bad for environmentdrainage projects bene cial.
3. Roadless areas, when traversed by o-road vehicles, are very sensitive to erosion.
21
4.4.3 Public and Federal Lands 1. Wilderness is area undisturbed by people; the only people are visitors. (a) U.S. Wilderness Act of 1964 de ne wilderness to be preserved. (b)
Limited visitorship and human uses.
(c) Act recognizes ecological value. 2.
Parks are open to public for recreation.
3. Parks/preserves are
ecological islands;
if one is too small, it will be inef-
fective for conservation.
4. Management should involve minimal human activity and: (a) Preserve undisturbed nature of wilderness, (b) Provide people with wilderness experience.
4.4.4 Land Conservation Options 1. Restoration: controversial goals.
Perhaps
restore ecosystem to historical
range of variation and ability to sustain self. (a) Kissimmee River, FL: undo channelization, restore soil layers in correct order. (b) Prairie restorationvery popular recently. Much original prairie remains along railroad; they were not plowed. (c) Early-succession grasses to restore damaged land (mining, urban). 2. Wetland restoration (a) Saltwater marsh restoration di cult because much more complex. (b)
1969 National Environmental Policy Act
mitigation require-
ment: if developer destroys wetland, must obtain or create to compensate. (c) Trying to construct wetlands to clean up runowetlands have some natural buering capacity. (d) Restored wetlands have been fertilized with treated waste water.
4.4.5 Sustainable Land-Use Strategies 4.5
Mining
1. Minerals are essential for our high standard of living. Almost everything uses them. 2. Mineral formation
22
(a)
Ore deposits
are formed when metals are concentrated in abnor-
mally high amounts by geologic processes. (b) As gravity condensed matter dispersed around into Earth, matter was heated. Iron and heavy metals sank toward molten center.
Not uniformly distributed because of selective dissolution, transport, and deposition. light rocks.
(c) Crust formed of lighter materials.
(d) Plate boundaries: crust is
i. Divergent: cold water gets heated by molten rock and leaches metals. Dissolved and deposited as sul des. ii. Convergent: rocks saturated with seawater are forced together, heated, and subject to intense pressure.
They partially melt.
Metals in magma mobilize. A. Hg distilled out of plate as plate moves downward. (e) Igneous processes i. Magma cools
→
minerals crystallize at dierent depths.
ii. Groundwater is heated and carries minerals.
Moves to cooler
rocks and deposits. (f ) Sedimentary processes concentrate materials for extraction. i. Water and wind segregate sediments. ii.
Placer deposits
are found in crevices or ssures. They are con-
California gold.
centrated mineral deposits formed by deposition of stream water that leaches metals from river basin.
iii. A shallow marine basin may be isolated by uplifting at its bound-
evaporates.
aries. The water eventually dries up, precipitating dissolved minerals called
(g) Biological processes: i. Phosphates: guano. ii. Iron ore: gray belts are unoxidized, red belts are oxidized. Apparently major iron deposition stopped when [O2 ] reached current level. iii. Organisms form many minerals, such as Ca in shells and bones. 31 identi ed as biologically produced. (h) Weathering processes concentrates some minerals in soil. More soluble minerals are selectively removed by biological processes. i. Al, Ni, Co are important soil minerals. ii.
Secondary enrichment
produces S
2−
from lower grades.
A. Near surface, primary ores and slightly acidic soil water, with oxygen, form H2 SO4 and sulfates of Ag and Cu. B. Migrate downward, leaching minerals.
23
enriching metal content of ores.
C. Below water table, where no more oxygen, deposit as
sul des,
3. Extraction (a)
Exploration
usually minimal impact, except for sensitive areas such
as wetlands, permafrost, arid lands. (b) As ores of lower grades are used, impact on resources increases. (c) Subsurface mines are much smaller, less visible, less waste rock. (d)
Surface mining
is cheaper, but has more direct environmental eects.
i. Large-scale environmental damage (beyond mine).
Change to-
pography. Dust pollutes air, even though attempts to control. ii. Leaching of trace chemicalsCd, Co, Cu, Pd, Mo can nd their ways into soil and groundwater. Runo ponds help, but do not eliminate. iii. Indirect: change nutrient cycling, biomass, species diversity, ecosystem stability. iv. Accidental discharges of stored waste. (e)
Strip mining removes surface layer of soil to expose coal (or other resource). Half of coal mined this way. i.
Acid mine drainage occurs when H2 O + FeS2 → H2 SO4 .
De-
bris left over from mining. (f ) Social impacts of mining: rapid urbanization, then rapid closing. (g) Minimizing impacts: i. ii. iii. iv.
Reclaim Stabilize contaminated soils Control air emissions. Prevent contaminated water from leaving. Treat waste. land.
often remove and dispose.
Neutralize acid with
lime.
v.
Perhaps with GM bacteria.
vi. Recycling: A. $50 B worth of metals are recycled. B. Iron/steel 90% by mass, 40% by value. C. Each ton saves: 1,136 kg iron ore, 455 kg coal, 18kg lime-
1 3 energy. D. Al recycling uses stone.
4.
5% energy.
Reserve is the portion of resource that is identi ed and can be extracted legally and economically at the time of evaluation. Resource is anything that can be extracted to obtain something useful.
(a) Concentration is everythingit determines usefulness.
24
(b) Except for Fe, nonmetals are used far more quickly than metals. (c) U.S. must import many strategic minerals (those necessary for military industrial complex) such as bauxite, Mn, graphite, Co, Sr, asbestos. i. Resulted in unlikely alliances between suppliers and consumers. Concessions on issues that would otherwise not happen. 5. Sustainability (a) Find ways to not use the mineral. Fiber optic obviates Cu; digital camera obviates Ag. (b) E ciency. (c)
R-to-C ratio:
namic.
R = known reserves; C = rate of consumption.
Dy-
6. Relevant laws and treaties (a) 1977 Surface Mining Control and Reclamation Act required restoration. Success is di cult and often dubious.
4.6
Fishing
1. Fishing techniques (a)
Bottom trawling
rolls a 60m trawl net on ocean oor, catching and
destroying everything in its path. 2. 44% of marine shing in upwelling zones. 3. Ironically, shing was one of the rst human activities to be scienti cally managed. (a) Wrong assumptions of logistic curve. (b) Tragedy of the Commons: little incentive to limit harvest.
eort. Predator sh
4. Currently not sustainable: increase in harvest Total population dropping.
(a)
accompanied by increase in
at 10% of preindustrial levels.
(b) Harvest levels peaked from 19701990. (c) 5.
Hunting
not likely to be sustainable: bison, whales.
Aquaculture
important protein source, growing.
Ancient practice in
China. (a)
Mariculture
(intertidal) much more productive than hunting for
oyster, mussel.
25
(b) Currently produce > 20%. 6. Laws and Treaties (a) 1972
Marine Mammal Protection Act sought to bring optimum
sustainable
population
rather than
yield.
International Whaling Commission's moratorium on commercial whaling protect 12 out of 80 species of whales.
(b) 1982
4.7
Global Economics
1. Tragedy of the Commons: individuals' personal share of
gain
from ex-
ploitation usually outweighs share of loss. Everybody wins in short term but loses in long term. (a) Forests (38% publicly owned), international water, Antarctica, air.
tion maximizes pro t.
2. Low growth rate means
not exploiting yields low pro t,
therefore
exploita-
Instead of slowly making money on the natural
growth rate, better to exploit all of the resources now and invest money. 3. Relative scarcity of resource aects value and price. Can you pro t from the resources harvested after your death? them extinct.
Then no interest in making
Do pro ts end when you die?
before you die.
Then harvest all you can
Can you earn your desired income from the resources
inde nitely? Then sustain. 4. Ralph d'Arge: developing countries did not share bene ts of Industrial Revolution, but now are sharing harms. They think that industrial nations, who have bene ted, should bear most future costs.
5
Energy Resources and Consumption
5.1 1.
Energy Concepts
Energy is the ability to accomplish work , which is force × distance.
2. A distinguishing feature of life is that it increases
local
order.
3. Units (a) Energy is measured in i. ii.
joule, 1 newton-meter.
Exajoule = 10 joules ≈ 1015 Btu (quad ). Newton is force necessary produce force of acceleration of 1 m/s2 18
to a mass of 1 kg. (b) Power is the rate of energy use ( second.
26
energy ) time
measured in
watt, 1 joule-
i. Multiplying watt by time (kWh) returns a unit of
power
energy
.
4. Amount of energy per unit times radiated from a body varies as the
5.2
of the absolute temperature of the body.
fourth
Energy Consumption
5.2.1 History 1. Greeks, Romans depleted wood
→
used solar power widely.
2. U.S.: wood peaked in 1880, coal peaked in 1920. 3. Exponential growth (consumption) from 19501980: 30 Since 1980,
→
→
80 exajoules.
100 exajoules, showing that new policies partially worked.
Production leveled o around 1970s. 4. Industrial energy consumption has leveled o since 1970s due to increased e ciency, cogeneration. 5. Car e ciency (avg.) rose from 14 mpg in 1970s to 28 mpg in 1996. Improvements slowed since then, largely because regulation loophole permits less fuel-e cient SUVs and light trucks.
5.2.2 Present Global Energy Use 1.
Cogeneration natural gas combined cycle power plant
can double e ciency by using waste heat. For example, generates electricity from both gas
turbine and steam turbine. 2.
Energy Policy Act of 2005 was rst national energy policy in over a decade: (a) Promote conventional energy to reduce reliance on foreign energy. (b) Promote nuclear power; build new ones by 2010. (c) Subsidies for alternative energy, make geothermal competitive, increases amount of ethanol in fuels. (d) Promote conservation: in federal buildings, for cars, credits for homeowners to install energy e ciency measures or automobiles. (e) Research to improve coal plants, goal for zero emissions, hydrogen cars, research shale and tar pits. (f ) Incentives to expand energy infrastructure and improve reliability.
3.
Hard path favors increased energy production while decreasing environmental impact.
Supporters argue that much environmental damage is
from developing countries using local energy, such as wood. 4.
Soft path
favors renewable resources, exibility, and match to uses to
increase second-law e ciency. Amory Lovins, champion, argues that most energy needs are of low quality, so expensive electricity is often wasted.
27
5.2.3 Future Energy Needs 1. Oil production expected to peak in 202050. A uence will be determined as much by energy conservation and e ciency as by production. 2. If
hard path
, then 120 exajoules by 2030. Else if
soft path
, 60 exajoules
(1991 prediction; overly optimistic, closer to 110 exajoules now). 3. To stabilize global warming, cut fossil fuels 50%.
5.3 1.
Fossil Fuel Resources and Use
Source rock
depositional basins
is nely grained organic matter (mostly plant) are buried in
sediments
at least 500 m deep.
Carbon must not
be completely oxidized.
(a) Pressure and temperature compresses sediment into oil and gas. (b) Light fuels migrate up to
reservoir rock
with lower pressure.
i. Porous; usually sandstone or limestone. ii. A
trap
A. B. C.
blocks upward ow.
Cap rock is ne-grained sedimentary rock. Anticline is an arch-fold that favors retention of fuel. A fault also traps the reservoir.
(c) Usually at young rock at plate boundaries. Exceptions: i. Texas ii. Gulf of Mexico iii. North Sea 2. 3.
Primary production pumps oil from well; only recover 25%. Enhanced recovery pumps stu (steam, water, gas) injected to push oil toward well.
4. Oil is 2nd most crust liquid, but 62% of proven reserves occupy 1% of oil eld. (a) Proven reserves = 1 trillion barrels; estimated 3 trillion barrels recoverable from remaining resources. (b) World consumption = 30 billion barrels/year.
consumption = 3 × discovery. Oil shale is ne-grained sedimentary rock with organic matter (kero-
(c) Today, (d)
gen).
Destructive distillation:
when heated to
retorted
500◦ C,
yields 60 L
oil/1 ton shale. U.S. has 2/3 of world supply. Produces more volume waste than mined because shale
28
crushed and heated.
(e)
Tar sands
are rocks or sands covered with tar oil, asphalt, or bi-
tumen. 75% in Alberta, Canada. Mine sands (di cult), then wash oil with hot water. Supplies 15% of North American oil production today. 5. Natural gas has only recently been seriously used for energy; used to be burned as waste, some places still do. 70120 year supply. Main transition fuel, since clean and releases less CO2 . (a) Coal-bed methane is methane stored in coal mines. (b)
7×
more can be stored in coal mine because of internal surfaces.
(c) 5 year supply at present rate can be recovered economically now;
3
estimated 20 trillion m . (d) Cheap to extract. Reduces methane emissions when mining. Disposal of saltwater waste is a problem. (e)
Methane hydrates exist 1000 m beneath sea oor: methane trapped in ice.
On land, known as
marsh gas.
Spontaneously erupt from
ocean oor. May have twice as much energy as all known fossil fuel reserves today, but mining will be di cult. 6. Coal swamps form from partially decomposed vegetation ( sea levels add sediment, compression peat into coal.
peat
). Rise in
(a) Most abundant fossil fuel; 250 years at current rate. (b) Rank: anthracite, bituminous (high sulfur), sub-bituminous, lignite. (c) Most polluting of fuels, in all stages. 7. Environmental disadvantages (a) Toxic brine is pumped with water; oil leaks. (b) Pollutants, including hydrocarbons and H2 S can be released into air. (c) Drilling muds (liquids injected into bore hole during drilling to keep it open) contain heavy metals. (d)
5.4
Re neries leak
(or spill).
Nuclear Energy
1. A neutron strikes
235
slowedto improve ssion. 2. Nuclear fuel (a) 1 kg UOx
≈ 16
moderated
U, producing ssion fragments and 3 free neutrons
and lots of energy. Chain reaction. Fast neutrons must be
MT coal.
29
(b) Only
235
U is ssile. Enrichment increases
[235 U]
to 3%.
3. Types of reactors (a)
Light water reactor
(U.S.) uses water as moderator.
i. Reactor core (fuel and moderator) encased in steel reactor vessel, then contained in reinforced concrete. ii. Fuel pins (enriched uranium pellets in tubes) packaged into fuel subassemblies.
critical Coolant must remove heat at the same rate it is produced. meltdown Pebble-bed reactors iii. A minimum amount of fuel keeps reactor
self-sustaining.
iv.
Else
core gets so hot it melts and breaches containment.
(b)
are gas-cooled and have billiard-sized pebbles as
fuel. Graphite shell with sand-grain particles of UO.
i. Mixed with unfueled graphite spheres to control heat. ii. Continuously refueled.
Always at optimal productionsafety
feature.
iii.
Passive stability Modular
means a reactor does not fail/meltdown due to
pump failure. iv. (c) (d)
each core 120 MW. 25% more e cient.
Burner reactors consume more ssile material than they produce. Breeder reactors make low-grade or waste U ssile. Can last 2,000 years.
4. Nuclear fusion:
2
H
+3 H →10
n
+42 He.
(a) Need very high temperature and density to form plasma.
energy released by fusion must exceed energy required to maintain plasma.
(b) Plasma must be con ned and
(c) Nearly in nite fuel reserves; cheap to produce. 5. Environmental impacts (a) Uranium mines produce radioactive waste. Mine tailing have been used for structures. (b) Enrichment produces waste. (c) Concern that waste cannot be isolated for required period of time. (d) Nuclear plants must be decommissioned. May be the highest cost. (e)
Radioisotopes can nd their way into food chain; circulate like their normal isotopes.
6. Radioactive Wastes and Human Healthcauses cancer.
30
(a) Units of radioactivity i. ii.
Curie Becquerel
(Ci) =
37 × 109
nuclear transformations/sec.
(Bq) = 1 radioactive decay/sec.
3
iii. For isotopes, pC/L (picocurie per liter), or Bq/m .
rads rems. gray Energy retained by tissue after radiation exposure. sievert absorbed dose × relative biological eectiveness.
iv. Actual dose of radiation:
and
A. SI
(Gy) = 100 rads = absorbed dose.
B.
(Sv) = 100 rems = eective equivalent dose =
v. Gamma rays: roentgen (R) or SI coulombs per kilo (C/kg). (b) American average 24 mSv/yr. i. 66% natural (0.35 mSv/yr is human;
40
K and
14
C).
ii. 33% is other, mostly medical. (c)
α
must be very close to cell. Blocked by paper. Dangerous if inhaled
or ingested; radiation absorbed by tissue. (d)
β
particles are electrons.
Block by thin metal or block of wood.
Moderately toxic; mostly absorbed when ingested. (e)
γ
rays require a meter of concrete or centimeters of lead.
When
ingested, some radiation exits body. (f )
Chronic
radiation health problems are not well known or understood.
7. Accidents: acceptable risk of 0.01%/yr is unacceptable if there are 1,000 plants. Also, often not planned to respond in accidents. (a) Three Mile Island: valve malfunction + human error. i. Containment structure functioned as designed. ii. 1 mSv released into atmosphere; surrounding 0.012 mSv. iii.
But
, on site, very high radiation: 12 mSv/hr.
(b) Chernobyl:
human error caused meltdown; explosion blew top of
building o, graphite burned. Radioactive particles rise into air. i. 237 con rmed radiation sickness; 31 deaths. ii. Did not tell world until 2 days later when confronted by Sweden's measurements of increased radiation. iii. 24,000 estimated to have received 430 mSv. A. Expected (based on Japan) 122 spontaneous leukemias. B. No signi cant increase yet, but possibly future. iv. Childhood thyroid cancer increase. v. Outside 30 km, probably negligible eect. A. Vegetation with 7 km dead or severely damaged.
31
(c) In last 34 years, about 10 accidents released radiation. 8. Radioactive wastes (a)
Low-level wastes in not hazardous is properly disposed.
closed because they have polluted groundwater.
solutions, sludges, acids, slightly contaminated equipment.
(b)
3/6 sites
Residues,
Transuranic waste is human-made materials heavier than U. Mostly from weapons.
(c)
High-level wastes is spent fuel, military reprocessing waste, weapons materials. i. Currently stored, mostly at commercial reactors. ii. Geological disposal controversialsome don't think it should be buried. iii.
Nuclear Waste Policy Act of 1982 initiate disposal program. A. 1987 amendment and Energy Power Act of 1992 specify deep underground repository: Yucca Mountain. B. Could receive waste starting 2010.
impact of heat generated by
C. Need to evaluate earthquake, volcano, groundwater, escape
waste
from deteriorating containers,
, geological processes that control transfer of radioac-
tive material. (d) Waste isolation pilot plant in Carlsbad, New Mexico: i. Rooms excavated in rock salt (easy to mine) store wastes. ii. Slow- owing salt naturally seal in 75200 years. (e) Sites that have been stable in past may not be stable in future. 9.
5.5
Energy Policy Act of 2005 advocates increase of nuclear power. Hydroelectric Power
1. Dams are multifunctional, but functions may not be harmonious (draining for agriculture con icts with high levels for high power and recreation) and dams have many environmental impacts: (a) Lose land and resources to make lake. (b) Trapped sediment ( where needed.
silting
) limits life of reservoir and prevents deposit
(c) Change entire river downstream. (d) Fragment ecosystems. (e) Increases evaporation
→
change local climate.
32
(f ) High pressure nitrogen can kill sh when swimming under waterfall as gas expands (bends). 2. Most good sites already dammed; not expected to grow in U.S. 3. Dams also give false sense of security: oods can occur from tributaries, dams may fail, and higher-than-designed-for- oods may occur. 4. Good dam sites are often good scenic nature sites. 5. Dams are 6.
expensive.
Their cheap water is
Water power is ultimately solar power.
subsidized.
7. 10% of U.S. power. Majority in Norway, Canada. 20% worldwide. 8.
Pump storage:
pump water into reservoir during low demand; ow out
during high demand. 9. Several dams have been removed or have been planned for removal. Many old ones are not useful at all.
If lots of sediment, most remove slowly
to minimize impact. May be many times more expensive to remove dam than to build it. 10. Colorado river is most heavily managed river; 80% of water in reservoirs behind Glen Canyon Dam and Hoover Dam. (a) River
has
been tamed: average ow increase, high ow decreased.
(b) Natural oods helped restore ecosystem, as did experimental oods.
3
(c) Treaty supplies 1.845 km
of water to Mexico. Very salty.
i. Desalinization plant built in Yuma on standby after its canals were ooded. ii. Coachella Canal can provide Mexico with water. iii. All American Canal delivers water to San Diego. Leaks billions of gallons that recharge groundwater used by Mexican farmers. Proposed concrete lining has been heavily impugned.
5.6
Energy Conservation
accomplished.
1. E ciency: food measured in
2.
First-law e ciency = (a)
energy stored
energy delivered . energy supplied
Second-law e ciency =
; consumption measured in
work
Average 50% in U.S.
minimum energy necessary . energy used
Average 1015%
in U.S. i. Lighting candle with match is more e cient than with acetylene torch.
33
ii. Water can be heated better by sun, not humongous furnace ames.
(b)
Thermal e ciency
is the maximum e ciency of a heat engine (such
as power plant, internal combustion); discovered by Sadi Carnot. Modern power plants, about
5.7
1 3.
Renewable Energy
1. Solar energy arrives at 7,000 times current demand. 2.
Passive solar energy uses architecture to adjust to seasonal changes. (a) South-facing building and windows and overhangs shade summer sun but allow winter sun to penetrate. (b) Walls can absorb energy then radiate into rooms. (c) Deciduous trees block sun during summer but allow sun during winter.
3.
Active solar energy requires mechanical power to circulate a uid from solar collection site to usage site. (a)
Solar collectors have a glass plate and black background with tubes ◦
in between. Water heated to 3898 C. (b)
Evacuated tube collector
has each tube pass through a larger tube to
reduce heat loss.
4.
Photovoltaics are the fastest-growing source of energy at 35% annually. (a) Standardized modules; build the system you need. (b) Dierent electronic properties of semiconductor layers cause electrons to ow into wires when hit by photons. (c) Developing countries: cheap, simple, o-grid rural electricity. (d) Springerville Generating Station in Tucson produce 24 MW.
5. Power tower concentrates sunlight to a central collector to boil water. (a) Can store heat with liquid salt. (b) By 2030, estimated by be economically competitive. 6. Luz International Solar Farm: synthetic oil pumped through solar collectors; boil water; steam superheated by natural gas. Combination allows uninterrupted power. 7. Environmental disadvantages of solar: (a) Dispersedproblem for centralized power. Need lots of land.
34
(b) Metals, plastics, and uids for equipment (esp. photovoltaics) may be toxic; production releases greenhouse gases. 8. Hydrogen is clean and can be burned like fossil fuels. (a)
Fuel cell works like battery to generate electricity by oxidizing H2
e ciency.
and capturing e
−
in external circuit (redox).
Increase second-law
i. Electrolyte solution; electrodes separated by Pt membrane. (b) Most economical way to produce hydrogen: H2 O + CH4
→ C + CO2 +
H2 . (c) Can be used to buer electrical generation. 9.
Tidal power
dam opening, then release water on turbines when tidal
movement increases/decreases ocean height su ciently. (a) Few locations have su ciently strong tides. (b) Can damage ecosystems of estuaries/bays. (c) Rapid lling and emptying of the bay damages intertidal habitats. 10. Wind power (a)
Winds
are produced by dierential heating of Earth's surface, result-
ing in air masses with dierent heat and density. i. Wind concentrated on mountain top or mountain pass. (b) Small mills (for farm) produce 1 kW. Modern windmills 6075 kW. i. High-tech ones 100 m, 30 stories, 35 MW. One is in Germany. (c) Wind power currently cheaper than natural gas, approaching coal. (d) World total 48,000 MW (34,000 MW in E.U.). i. 1 large fossil or nuclear = 1,000 MW. ii. 1% of total electricity. (e) High potentialmany countries have more potential than current use.
11.
Micro-hydropower
is best in mountains. Evaluate case-by-case.
(a) Prone to being lled by sediment. (b) In large scale, can have signi cant environmental detriment. 12.
Biofuels
are organic matter, burned or converted (gasify, distill), then
burned. (a) 35% of developing countriesusually rewood.
35
(b)
Digestion
bacteria digest matter to produce methane.
(c) Land lls, wastewater treatment plant can produce biogas (mainly methane). i. China, produced in sewage treatment. ii. India, produced locally from cow manure. (d) Waste incineration releases pollutants, as not all hazardous trash can always be removed. (e) Land unsuited for food crop can grow biomass crop (like trees). (f ) By 2030, biomass can produce 100,000 MW (12%), using 2/5 of banked farmland. 13.
Geothermal energy harnesses natural heat from earth's interior. (a) 9,000 MW0.15%. (b) Competitive with other sources. (c) At plate boundaries, heat ow is unusually high. (d) Hot geothermal system (>
80◦ C)
resource base > fossil + nuclear.
i. Hydrothermal convection: steam and/or hot water pumped to depths to transfer heat to surface. ii. Geysers Geothermal Field produce 1,000; near San Francisco. (e) Lower temperature systems can be used for heating. i. Groundwater is geothermal: at 100 m, groundwater is
13◦ C
and
can heat/cool homes. (f ) Environmental impact i. Releases some CO2 , SO2 . ii. Thermal pollution. Hot wastewater can be corrosive and saline. (g) Future i. Known reserves 20,000 MW, 10% for West. ii. Undiscovered potentially
6
4×.
Pollution 1.
6.1
Heavy metals include Hg, Pb, Cd, Ni, Au, Pt, Ag, Bi, As, Se, V, Cr, Tl. Pollution Types
6.1.1 Air Pollution 1. Particulates are
small dust particles (including asbestos).
heavy metal.
36
Sometimes
(a) Coal power plants. (b) Industrial boilers. (c) Cars. 2.
Stationary pollution includes point sources (single sites), fugitive sources (open areas
exposed to wind
), area sources (well-de ned area that has sev-
eral sources).
3. Eects include damage to vegetation, increased susceptibility to diseases and pests, disruption of reproduction. In humans, poisoning, cancer, birth defects, irritation, susceptibility to viral infections, heart disease, aggravation of respiratory diseases. 4.
Criteria pollutants are 6 most common ones. (a) Sulfur dioxide is oxidized into sulfate, forming sulfuric acid. coal, oil re ning, industrial processes.
Bleaches leaves.
From
Increases
chronic respiratory disease, shortening of breath. Reduced 50% since 1970s. (b) Nitrogen oxides (most commonly NO, NO2 ) contribute to smog and
2−
ion NO3 , reducing visibility. Emitted from stationary and mobile sources. Acid rain. May suppress plant growth; may be bene cial at low concentrations. (c) Carbon monoxide bonds
250×
more easily to hemoglobin than does
oxygen. i. Worst for heart or respiratory disease or at high altitudes. ii. 10% man-made. Most emissions from tailpipes. (d) Ozone/photochemical oxidants result from interactions between NO2 and sunlight. i. Unstable, so oxidizes better than does oxygen. ii. Retards plant growth at low concentrations; kills leaves and plants at high concentrations.
Lungs decrease elasticity, scars
in airways. iii.
Peak ozone level
is one of the best indicators of air pollution.
(e) Particulate matter (PM 10) is composed of particles (<
2.5µm)
< 10µm.
PM 2.5
is of special concern because they are absorbed through
lungs into bloodstream. i.
Total suspended particulates
measures this pollution. Much higher
in cities of developing countries. ii. 29% of human mortality in cities. iii. Dust can suocate plants. Large particulate pollution (e.g., from construction) can damage entire ecosystems.
37
iv.
Global dimming cools atmosphere.
Jet travel is a signi cant
cause.
(f )
Lead
5.
or
is emitted through leaded gasoline, which protects engines.
Transported as particulate
uptaken by organisms.
Primary pollutants are emitted directly into air. (a) CO (58%), VOC (11%), NOx (15%), SOx (13%), particulates (3%). (b)
Natural
6.
Exceed human pollution.
emissions: SO2 from volcano, H2 S, wild res, hydrocarbon
seeps: La Brea Tar Pits.
Secondary pollutants result from reaction between primary pollutants and normal atmospheric compounds.
7. Acid rain can precipitate or be deposited as sulfate and nitrate, acid anhydrides. (a) Can travel
very
far:
1 3
> 500
mi,
1 3 [200, 500] mi.
(b) CaCO3 (limestone) can buer acids; granitic rocks cannot. (c) Forests: trees weaken, die
→
less habitat; leaves fall o
→
change
surface microclimate. (d) Lakes: interferes biologically, dissolves nutrients
→
ow out and are
lost. Algae die. i. Acid leaches metals from soils. Al hazardous to shclog gills. Heavy metals!
(e)
Acid fog
occurs when water vapor, mixed with pollutants, condense
near ground around smog particulates. Drops of acid may be left as fog dissipates and can be inhaled deeply within lungs. 8. Air toxics are hazardous at low concentrations; many carcinogenic. Classi ed into gas, metal, organic, then whether carcinogenic. (a) H2 S from re neries and smelters, or geysers, swamps, bogs. (b) HF from Al production, coal gasi cation, burning coal. toxic. Can damage grazers because plants are exposed. (c) Methyl isocyanate burns on contact (irritation). violent coughing, swelling of lungs,death.
Extremely
Few ppm causes
Used in pesticides.
In
Bhopal, India leaked from tank. Catastrophic. (d) Volatile organic compounds (VOC) are used as solvents. Hydrocarbons react to produce smog. Cars. Lowered 50% since 1970s. (e) Benzene is solvent and gasoline additive. (f ) Arcolein produced in industrial combustion of petroleum. Extremely irritating.
38
9.
Heat island occurs due to burning fuels and solar collection of buildings and pavement.
10.
Temperature inversions
Caps on pollution altitude. (a) Coast:
occur when warmer air is above cooler air.
descending warm air forms semi-permanent inversion.
Sea
breeze pushes pollution towards canyons. (b) Valley: cloud cover decreases temperature at surface and increases temperature in clouds, forming warm air.
At surface, dew point
(temperature where vapor condenses) may be reached (c) 11.
Chimney eect:
→
fog.
polluted air may spill over mountains.
Smog (a)
Photochemical
(L.A., brown air): NOx emitted by cars accumu-
late; sun breaks down to NO + O; O + O2
→ O3 .
Organic compounds
react with NO to increase NO2 . Ozone maximum at noon. (b)
Sulfurous (London, gray air, industrial).
From burning fossil fuels.
12. Indoor air pollutants (a)
Legionella pneumophila
, pond-water bacteria can spread to air con-
ditioners. Cause Legionnaire's disease. (b) Molds may release toxic spores. Chronic in ammation and scarring of lungs.
1 2 of all health complaints.
(c) Pesticides. (d) Formaldehyde used in insulation, manufactured wood.
Emit gas.
(e) Dust mites, pollen. (f ) Environmental tobacco smoke exposed to workers may be equivalent to 10 cigarettes per day. (g)
Radon is natural: lead-206.
α
radium
→
radon
decays.
i. Estimated 10% of lung cancers.
→
polonium-218
→
lead-214
→
Very large threat if true.
ii. Synergistic with smoking. iii.
α
particles break DNA strands.
iv. Radon enters through rock and soil into basement, dissolved in groundwater, or contaminated construction materials. v. Techniques to remove: A. B.
Gas permeable layer (often gravel) beneath oor. Plastic sheeting on top of gas permeable layer prevents radon from entering.
C.
Sealing and caulking in foundation oor. 39
D.
Vent pipe from gas permeable layer to roof.
(h) Often more highly concentrated. i. Many potential indoor sources. ii. Energy e ciency = sealing building.
Cannot dilute pollutants.
(i) Control: i. ii.
Ventilation: use more fresh air; open windows. Source removal: restrict or prohibit use of certain
material,
ban smoking indoors. iii.
Source modi cations:
change designs (more energy e cient,
use non-polluting materials); apply barriers (coat lead paint). iv.
Air cleaning:
ltering.
v. 13.
Chimney eect occurs due to temperature gradient between indoor and outdoor. (a) If inside is warmer, warm air rises and
draws in
air from lower. En-
vironmental tobacco smoke can be drawn in from outside. 14. Sick building have two types: (a)
Building-related illness (BRI) has identi able problems, such as pathogenic molds or bacteria.
(b)
Sick building syndrome (SBS) cannot be traced.
Non-pollution
factors (environmental stress, labor-management relations) may contribute. 15. Remediation and reduction strategies (a) (b)
Conservation e ciency. Capture particulates Cover Recirculate exhaust Dilute air-fuel mixture Catalytic converter: and
from point sources in settling chambers or col-
lectors.
(c) (d) (e) (f )
waste or dirt piles to reduce dust. to reduce NOx . less NOx , more hydrocarbons.
decompose hydrocarbons and oxidizes CO.
i. Old cars pollute more because people don't take care of pollution devices.
Charge fees Washing ii.
(g) (h)
for pollutionrequire annual testing.
coal removes pyrite, but organic carbon remains.
Coal gasi cation produces expensive synthetic gas. 40
Expensive.
(i)
Scrubbing: 1 2 H2 O
+ CO2
calcium removes sulfur:
CaCO3
+
SO2
→
CaSO3
·
(or CaO).
16. 4 processes remove particles and chemicals for air: (a) Sedimentation: heavier-than-air particles eventually settle out. (b) Rain out: precipitation physically or chemically removes substances. (c) Oxidation. (d) Photodissociation: energy from solar radiation breaks bonds. 17. Coal-burning power plants produce 70% of SO2 , 30% of NOx , 35% of CO2 . 18.
Clean Air Act Amendments of 1990 are comprehensive regulations. (a) 50% cut in SO2 achieved. (b) 2 Mton reduction in NOx more di cult because cars emit most. (c)
Permits
comprise total amount of allowed pollution. Environmental-
Makes pollution expensive.
ists can also buy permits to prevent them from being used, but not a major factor. (d) Goal: end
all
CFC and chlorine chemicals by 2030.
(e) National Ambient Air Quality Standards as
minimum acceptable level
set to reduce health hazards in old and youngmost susceptible. Supreme Court unanimously upheld standards. 19. Economic impacts: incremental cost diers. Much more expensive for Al plant to reduce emissions than for utilities. Some argue stricter standards for utilities and fewer for Al. Others prefer taxes or pollution vouchers same environmental eect but more cost eective because driven by market pressure.
6.1.2 Noise Pollution 1. Eects (a) Up to 60 dB is safe. (b) > 80 dB is potentially dangerous. (c) 140 dB is threshold of pain; 180 dB is injurious.
hour.
(d) Lawn mower, motorcycle damages after after
1 2
8 hours.
110 dB loud music
(e) 5060 dB noise interferes with sleep; fatigued awakening.
41
6.1.3 Water Pollution 1. Thermal:
↑
→↓ [O2 ]. ∆1.5◦ C.
heat
only tolerate
Warmer water decreases sh tness; some may
2. Types include heavy metals, sediment, radioisotopes, heat, fecal coliform bacteria, P, N, Na, pathogens. (a) Surface water is not immune to outbreaks. tated Milwaukee: it is resistant to chlorine.
Cryptosporidium Cryptosporidium potential.
devasmust
be ltered, but it doesn't usually enter water supply. (b)
Fecal coliform bacteria is a measure of disease
Usually
harmless bacteria in animal intestines. Pathogens are more likely to be present where more feces is deposited. i.
E. coli
E. coli
can be deadly. Walkerton, Ontario: 5 died, 500 ill because
storm waters contaminated wells with report.
and utilities did not
(c) N, P: from fertilizer, detergent, wastewater treatment.
eutrophication (human caused).
Cultural
i. Promotes plant, cyanobacteria, and algae growth. ii. Algae form surface mats
→
kills stu below.
iii. Decomposing bacteria grow, remove oxygen, eventually lots of stu dies. iv. v.
Eutrophic lakes Oligotrophic lakes
have naturally high levels of nutrients. have naturally low levels, pleasant water.
vi. Coasts, reefs may also suer from eutrophication: Great Barrier Reef, Hawaii. (d) Oilnormal shipping probably releases most pollution.
Long-term
eects unknown. (e) Sediment (small rock and mineral fragments) is by volume highest level of pollutant. i. Agriculture increases erosion.
Conservation cannot eliminate
loss.
but
ii. Urbanization even greater: struction,
large amounts erosion during con-
on-site control measures can be eective (35% re-
duction in a Maryland sediment control program). (f )
Acid mine drainage
is water with lots of H2 SO4 formed from
weathering of pyrite. i. Abandoned mines are problematic because groundwater is non longer pumped out, so it can ood and over ow. 3. Sources include all sectors of society:
42
(a) Surface water occurs when in ow of pollutant exceeds natural capacity to remove, convert, or dilute it. i. Runo: urban (oil, chemicals), agricultural. ii. Accidental spills, release of radioactive stu (from accidents). iii. Leakage from storage sites. iv. Air fallout. v. Sediment from agriculture and construction sites.
1 2 of domestic water supply. It is actually easy to pollute. Channels for groundwater are small, so dilution
(b) Groundwater is the source of opportunity is limited. i.
Leaks
waste disposal, buried pipes. Estimated that 75% of haz-
ardous waste disposal sites are polluting groundwater. Land lls over porous soils pollute water quickly. ii.
Seepage
: acid water and waste from mines, cesspools/septic sys-
tems, spills, radioactive materials. iii. Saltwater intrusion in coastal aquifers: when water is pumped, it no longer ows out into saltwater aquifer, allowing salty groundwater to in ltrate. 4.
Biochemical oxygen demand (BOD) for organic
decomposition
.
is amount of oxygen required
Amount of oxygen consumed by decompser
microorganisms.
(a) Inversely related to dissolved oxygen. (b) 5 mg/L is threshold for water pollution of DO. 5.
Wastewater treatment deals with addition of suspended solids,
salts,
nutrients, bacteria in water due to human use. (a) Septic-tank separates solid and liquids and digests (biochemically change) organic matter. i. Water then moves into absorption eld/drainage eld and seeps into soil.
land. Failures
ii. Further treated by oxidation and ltering.
iii.
Not suitable for all
occur when tank is not pumped, for poor drainage allows
wastewater to rise to surface. (b) Wastewater treatment plants remove BOD and chlorinate bacteria. i.
Primary treatment involves screens
grit chamber tank Digester material,
primary sedimentation
to remove large oating
to remove rocks,
where particulates settle to form sludge.
A.
processes sludge. Relatively new.
43
B. Removes 3040% of BOD.
ii.
Secondary treatmentactivated
sludge method (most com-
mon). A.
Aeration tank nal sedimentation tank. Activated sludge Final sedimentation tank
mixes wastewater with air and some sludge
from
B.
is rich in aerobic bacteria, which consume
BOD.
C.
settles sludge out (again).
Most
sludge goes to digester.
D. Removes 90% of BOD.
iii.
Advanced wastewater treatment use sand lters, carbon lters, chemicals to remove speci c pollutants such as N, P, heavy metals.
iv.
Chlorine produces toxic by-products.
v. Methane is released by digestion; used as fuel or burned as waste. vi. If sludge isn't polluted, used to improve soil, else land lled. 6.
Wastewater renovation and conservation cycle involves using treated wastewater to irrigate, then allowing water to
renovate
(natural puri ca-
tion through slow percolation in soil), recharging groundwater, and reuse of groundwater. 7.
Resource recovery
wastewater plants capture methane and use plants grown
in controlled environment (sell owers to nance operation) in lieu of secondary treatment. More greenery can purify water even more. 8. Wastewater can be applied to isolated wetlands.
Promote growth and
reduce downstream BOD. 9. 1792/1977 Amended Clean Water Act (Federal Water Pollution Control Act) provides billions in grants for sewage treatment plants, encourages innovation, including alternative wastewater treatment and aquifer recharge. 10. Other relevant laws: (a) 1956
Federal Water and Pollution Control Act Fish and Wildlife Coordination Act
enhances water quality
and controls pollution. (b) 1958
mandates conservation mea-
sures with U.S. Fish and Wildlife Service for dams, power plants, and ood control. (c) 1969
National Environmental Policy Act
requires
impact statements
prior to federal actions that signi cantly aect environment: dams, channelization, power plants, bridges. (d) 1970
Water Quality Improvement Act
expands 1956: control oil and
hazardous waste; research for Great Lakes and mine drainage.
44
Federal Safe Drinking Water Act Comprehensive Environmental Response, Compensation, and Liability Act Hazardous and Solid Waste Amendments to the Resource Conservation and Recovery Act Water Quality Act
(e) 1974
sets containment levels for
pollutants and pathogens. (f ) 1980
establishes revolving fund (Superfund) to clean up haz-
ardous waste sites to reduce pollution. (g) 1984
regulates underground gasoline storage
tanks. (h) 1987
establish policy to control non-point pollu-
tion. Led to development of state management plans to control.
6.1.4 Solid Waste 1. Types. (a) 35% paper (b) 12% yard trimmings (c) 12% food scraps (d) 11% plastics (e) 8% metals (f ) 7.4% rubber, leather, textiles (g) 5.3% glass (h) 5.8% wood (i) 3.4% other
toxic.
i. Infectious wastes should be sterilized and are
ii.
not considered
Hazardous waste is produced 700 Mton/year in U.S. A. 50% chemical industry. B. Electronic, petroleum, coal each 10%. C. Destroyed buildings. D. Tons of abandoned waste sites.
1,000 may threaten public
health and environment. E. Management of hazards may be most serious environmental problem. 2. Hazardous waste legislation (a)
1976 Resource Conservation and Recovery Act (RCRA) identi ed hazardous wastes and life cyclescradle to grave management.
45
(b)
1980 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) de ned policies and procedures for release of hazardous substances into environment. i. List of sites where hazardous substances likely or already impacted environment. ii.
Superfund
to clean up worst cases.
iii. 1984 and 1986 amendments: A. Improve standards for disposal and cleanup. B. Ban disposal of certain chemicals: dioxin, PCB, solvent. C. Timetable for
phasing out
disposal of all untreated liquid
hazardous waste in land ll or surface impoundment. D. Increase Superfund. E.
Environmental audits permit defense against liability.
tine.
old maps, photographs, reports, drilling, sampling.
Now rou-
Study
F. Toxic 500 become public. Pressure industries. 3. Disposal: (a)
Composting
is rapid partial decomposition of organic matter by
aerobic organisms. Popular in Europe and Asia due to intense farming. Large-scale in mechanical composters. (b)
Incineration
burns at temperatures high enough to consume all
◦
◦
combustible material (900 C1,000 C). i. Ideally 7595% reduction. ii. Practically 50% due to maintenance and waste supply problems. iii. Can supplement other fuels. iv. Pollute air. Trapping pollutants expensive. Need subsidies. Not optimal investment. (c)
Open dumps have waste piled and unprotected.
Closed and banned
in U.S. and many other places. i. Sometimes ignited. ii. Other places periodically compacted. (d)
Sanitary land ll
waste with soil every day or more often. i.
is designed to concentrate and contain.
Covers
Leachate is water percolating into refuse that carries pollutants and bacteria.
ii. Siting is everything.
Arid, impermeable places with low water
table. iii. Often located in poor and minority places. iv.
Monitoring involves continual sampling (even if land ll abandoned) of water and gas at special monitoring wells.
46
v. Entry of pollutants into environment: A. Gas release. B. Heavy metals retained in soil and uptaken by plants. C. Soluble materials move to groundwater. D. Polluted groundwater can seep into surface water. E. Wind blows toxins away.
vi.
Multiple barriers Vital to prevent leachate from reaching groundwater, where cleanup will be very expensive. include clay and plastic liners to limit leachate,
drainers to collect leachate, gas collection, groundwater monitoring.
vii.
Resource Conservation and Recovery Act of 1980 strengthen
and standardize design, operation, and monitoring of sanitary land lls. Fail
→
close.
4. All methods of hazardous waste disposal causes some environmental disruption. (a)
Secure land ll con nes waste, controls, collects, and treats leachate, and detects leaks. i. Drains concentrate leachate to collection basin. ii. Animals can chew or burrow through impervious liners. iii. Some argued no such thing as secure land ll.
(b)
Land application is intentional spreading of waste on land. able stu, like oil waste.
breakdown.
i. Micro ora (microorganisms in soil) attack material in
Biodegrad-
microbial
ii. Restricted to top 1520 cm. (c)
Surface impoundment uses depressions or excavations.
Aeration
pits and lagoons. Seepage. Controversial; many closed. (d)
Deep-well disposal injects waste to place isolated from aquifers porous rock sealed by impervious rock. i. Oil- eld brine. ii. Not quick and easy solutionfew sites, must monitor.
5. Alternative methods for toxic waste (a) Recover valuable materials for future use in waste. (b) Neutralization, oxidation, and separation of heavy metals. (c) Incineration can destroy hazards, but some may escape as pollution. 6. Ocean dumping and pollution along shipping lanes
47
(a) Most pollution in the most productive parts of ocean. (b) Threaten sheriesshell sh contain polio- and hepatitis-causing organisms. (c) Algal blooms kill almost all marine life in area. (d)
Microlayer
, top 3 mm, extremely fragile. Phytoplankton, sh larva
here.
i. Heavy metals 101,000 more concentrated here. (e) Plastics oat and accumulate in convergent currents.
vergence.
i. Northwestern Hawaiian Islands, very remote, is one
zone of con-
ii. 80 tons of marine debris collected there. iii. Birds eat plastics. Rings seal mouths. 7.
Industrial ecology is the study of relationships among industrial systems
of place.
and linkages to natural ecosystems.
Essentially, waste is a resource out
As extraction costs increase, nancial feasibility of reusing and
recycling increases. (a) For example, coal power plant heats homes, scrubs SO2 to make gypsum, CO2 sequestered and pumped to greenhouses, ash used to surface roads. (b) Canberra, Australia hopes to achieve zero-waste by 2010. 8.
Integrated waste management
composting, land lling, incinerating.
includes
reuse, reduction, recycling,
(a) At least 50% waste stream can be reduced: i. Better packaging (10%) ii. Large-scale composting (10%) iii. Recycling (30%). A. U.S. recycles 30% of waste stream. B. 50% reached in some parts of U.S. C.
Intensive recycling Must develop market for recycled products.
can reduce 8090%; pilot program 84%.
D. 50% of U.S. steel from scrap. E.
(b) Using sewer sludge is widespread, but getting rid of toxins is di cult. i. Separate urban and industrial wastes. ii. Require factories to pretreat their waste. (c)
Materials management is resource conservation. i. Eliminate subsidies for virgin material and incentivize use of recycled.
48
ii. Fine poor material management processes. 9.
Pollution prevention (P-2):
Wisconsin cheese factory deposited 2,000
gal of salt water into landscommon for corporations that cannot discharge into municipal treatment plantsand damaged crops. DNR limited salt discharge. Factory developed evaporator, which reduced waste by
We are moving away from regulating disposal to eliminating as much of it as possible.
75% and decreased salt purchases by 50%. Recovered costs in 2 months.
6.2
Impacts on the Environment and Human Health
6.2.1 Hazards to Human Health 1. Synergism: toxins acting simultaneously
often unknown.
2.
may be
>
P
parts.
Eects
Environmental risk analysis (risk assessment) is the determination of health hazards to people exposed to pollutants and possible toxins. (a)
Identify hazard Dose-response assessment Exposure assessment
(whether exposure is detrimental).
Observe other
humans, animal testing, cellular/molecular research. (b)
. Administer varying doses to humans or
animals. Di cult. Doesn't prove causality. (c)
. How many exposed, how much area contam-
inated, ecological gradients, length of exposure? Di cult like doseresponse. (d) 3.
Risk characterization
. Conclude health risks based on exposure.
Asbestos are ber-shaped minerals. (a) Fibers embed in lung tissue (b)
White asbestos
→
Asbestosis
is related lung condition.
cancer.
(chrysolite) is not particularly harmful. 95% of U.S.
i. No recorded nonoccupational disease. ii. Belief that much removal was unnecessary.
(c) 4.
Blue asbestos
Lead
(crocidolite) very harmful.
is apparently biologically useless but impacts every system, espe-
cially nervous system and in small children. (a) Poisoning of patricians may have contributed to Roman fall. (b) In children, may promote antisocial/criminal behavior. 5.
Electromagnetic elds have been suspected of increasing cancers, but question not yet answered.
49
6.
Voluntary exposure is commonly smoking, drinking, and drugging.
7. Acute eect occurs soon, usually large exposure. Chronic opposite. 8.
Dose response
means the eect of a chemical depends on the dosage
(concentration).
harmful. harmful
(a) (Very) low concentrations (b) High concentrations i. ii. iii.
, eventually
lethal
.
LD-50 is dosage where 50% of population dies. Crude. ED-50 is dosage that causes desired eect in 50% of population. TD-50 is dosage that is toxic to 50%. Often reduced enzyme activity, decreased reproduction, other speci c symptoms.
iv.
Therapeutic index =
LD-50 ED-50
and
↑=
safer.
(c) Curve crests where maximum bene t occurs (plateau). (d) Threshold values unknown for most substances, especially transition from bene t to harm.
6.2.2 Hazardous Chemicals in the Environment 1. Biomagni cation. (a) Cd: coal (b) Hg: Hg 2.
→
2+
ash
→
plant
→
herbivore
bacteria
−−−−−→ [CH3 Hg+ ]
→
carnivore (5060×)
accumulates more, stronger eect.
Persistent organic pollutants are now banned. (a) Example i. PCBs (heat-stable oils). ii. Dioxin, perhaps most toxic man-made chemical. Byproduct of chlorine combustion in herbicide synthesis. A. Damages wildlife in
very
small amounts.
B. Human impact controversial. (b) Often contain Cl. (c) Do not biodegrade. (d) Fat soluble; likely to accumulate. (e) Able to be transported long distances in wind, water, sediment. (f )
Hormonally active agents i.
Atrazine
(herbicide) feminizes frogs.
ii. Detriment reproductive viability. 3. Ecological gradients can be de ned by distance to pollution source.
50
4.
Tolerance is ability to resist or sustain stress due to toxin or environment. (a) Behavioral. (b) Physiological: body adjusts.
Does not mean damages ceases.
i. Detoxi cation. ii. Transport of toxin to non-harmful place (fat). (c) Genetic tolerance: selection.
6.3 1.
Economic Impacts
Cost-bene t analysis.
of life, not length.
(a) Risk of death from pollutants is low.
quality
Lowering air pollution increases
(b) Risks that aect a small proportion of people are more acceptable. (c) Novel risks are less acceptable. (d) More desirable activities carry greater acceptable risk. Sports, recreation vs. working.
But do we value length
(e) RAND study nds that direct measures (i.e., not bettering the envi-
of or quality of life more?
ronment) to increase longevity are cheaper.
(f ) Cost of pollution = costs to control pollution + loss from damages. i. May have have opposite trends. Minimum at intersection. A. If minimum cost results in too much pollution, then reducing pollution beyond this point may be considerably more expensive. ii. Total cost may stabilize or decline as pollution control becomes more e cient and external costs decline. iii. Estimated cost of pollution control per family is $3060. 2.
Externalities, or indirect costs are eects not normally accounted for in cost-bene t analyses and are often not recognized as a cost or a bene t. (a) Knowing
true cost
is necessary for rational consumer choice.
(b) Clean air and water and traded largely as if they cost nothing. (c) Dollar value can sometimes be determined: water by ow and storage
Now standard procedure.
in rivers and lakes; forest by inventory of trees and yield; mineral by estimated reserves.
(d) Who should pay? Polluters (then pass costs to consumers) or tax? Consensus that polluter pays approach oers stronger incentives.
51
(e)
Public service functions
have tremendous economic eects. We only
recognize them when we begin to lose one.
What may previously
have been an externality may now become a direct cost.
Natural capital Landscape aesthetics i.
(f )
estimated $3$33
trillion/year.
is di cult to quantize because of dierent pref-
erences.
i. Some say, coherence, complexity, mystery. ii. Others, unity, vividness, variety.
but
(g) Value of the future: pro t in future,
economically, pro t now is worth more than
humans tend to think about the future.
i. Many believe we have obligation to future generations to not damage environment. ii. Spending on environment can be viewed as diverting funds from other productive investments (which may bene t future generations).
Implication: protecting environment is taking from today's poor to give to tomorrow's future. How do you know which sacri ces are important for future?
iii. As wealth increases, so does value placed on environment.
iv. Future value depends of future consumers' view of consumption.
v. If future value is greater than present value, eventually future value will be in nite. That's not possible.
Rule of thumb: do not throw away something that cannot be replaced if you are unsure of future value Marginal costs Often increases exponentially. vi.
(precautionary principle).
3.
is the cost for one additional unit.
4. Empirically, individual transferable quotas have been most eective.
value
5. New York Catskill Mountains case shows that it doesn't take much capital to get people to act because they
7
a clean environment.
Global Change
7.1
Stratospheric Ozone
1. 90% in stratosphere1540km. 2.
Blocks 99% of UV. (a)
UVC
is shortest
λ.
Decomposes O → 2O, then not aected by ozone layer. 2
O
+
O2
→
O3 .
Negligible amounts reach surface (b)
UVA is longest λ and is
52
Some damage.
(c) 3.
UVB is energetic; O3 is only gas known to absorb it.
Dobson unit (DU) = 1 ppb O3 .
4. Hypothesis:
CFCs emitted in lower atmosphere are extremely stable
unreactive, 100 year residence time. (Soils remove an unknown amount,
catalytic chain reaction:
though). Eventually disperse to upper atmosphere. UV decomposes CFC, releasing Cl, which reacts with O3 in a (a) Cl
+ O3 → ClO + O2
(b) ClO
+ O → Cl + O2
(c) Estimated each Cl destroy 100,000 O3 . (d) May be interrupted removed up to 200 times, but UV may decompose Cl compound again at any time:
+ NO2 → ClONO2 Cl + CH4 → HCl (end for
i. ClO ii.
most Cl).
5. CFCs used in aerosol (not problem anymore), coolant (growing problem in developing countries), Styrofoam production. 6. Many solvent contain Cl and react similarly, as does halon (Br).
at equator, but circulates to poles.
7. Naturally, ozone highest at poles and lowest at equator.
8.
Polar stratospheric clouds are observed at 20km. (a) Form during polar winter:
polar vortex.
Mainly produced
Glow.
Antarctic air mass isolated and circles
about pole
(b) Vortex cools, condenses, descends (no sun to warm up). (c) Type I (190195 K): H2 SO4 particles freeze; seed for HNO3 . (d) Type II (< 190 K): water vapor condenses around Type I particles. Mother-of-pearl color.
70% O in weeks.
(e) HNO3 settle out.
3
Cl sink ClONO cannot be formed. Can destroy can dissipate southwards. 2
(f ) Arctic clouds are not as severe, but ClO
9. Tropical, mid-latitude depletion also hypothesized.
Polar stratospheric
clouds migrate; volcanic explosions (SO2 may gentrify). 10. Eects (a)
Reduce ocean productivity:
Antarctic waters decreased primary pro-
ductivity 612% associated with ozone depletion. i. Plankton are CO2 sink
→ 53
exacerbate global warming.
(b) (c)
Disrupt food production Cancer increase Reduce immune function. .
predicted to
until 2060 when ozone layer begins to
recover. (d)
(e) Cataracts. 11. Strategies for reducing ozone depletion (a) Estimated to return to pre-1980 by 2050. Already growth reduced. (b)
Recover
discarded CFCs. 1.2 kg CFC per refrigerator (50 M world-
wide). (c)
Hydro urocarbons:
F reacts similarly to Cl, but 1,000 less e -
cient. Possible to make it not deplete. (d)
Hydrochloro urocarbons can be broken down in lower atmosphere. But if it gets into upper atmosphere, still deplete. Transition; phase out 2030.
12. Relevant laws and treaties (a)
1987 Montreal Protocol27 original, 119 later. i. Reduce CFCs to 50% of 1986 levels. Eliminate by 1999. ii. Developed stopped by 1995; deadline for developing, 2005. iii.
China, India
are not parties.
iv. Requires technology and money for developing countries. v. Black market for CFCs. (b) 1990 London (c) 1992 Copenhagen
7.2 1.
Global Warming
Climate change earth by several
◦
refers to uctuation of annual mean temperature of
C over the past million years.
(a) Temperatures dropped in 1940 but began dramatically increasing starting in 1970s. (b) Milankovitch cycles:
earth's unstable orbit produces 100,000 year
Insu cientseen
cycles, which correlates with major (inter)glacial periods. 40,000 and
as one mechanism among many.
20,000 year changes are result of earth's wobble.
◦
◦
2. Mean surface temperature expected to increase by 1.5 C to 4.5 C by 2100. 3. Surface temperature determine by:
54
(a) Sunlight received and re ected. (b) Heat re ected by atmosphere. (c) Evaporation and condensation of water vapor. 4.
Greenhouse gases re-emits radiation to earth's surface, warming earth. (a) Water vapor responsible for 85% and water aerosol 12%. (b)
Atmospheric window
is the 812
house gases do not absorb well.
◦
But CFCs do!
µm wavelength where natural green-
(c) Lower atmosphere kept 33 C warmer than otherwise and moderate day/night temperature
∆.
(d) CO2 : 5060% of anthropogenic greenhouse eect. i. Exponential growth for 150 years; r = 0.5% per year. ii. By 2050,
1.5×
pre-industrial level.
(e) CH4 1220%; more than doubled in past 200 years. Human sources: land lls, burning biomass, coal and natural gas, agriculture:
rice
(anaerobes release CH4 ,), raising cattle. i.
Naturally,
methane releases may have ended glacial periods and
quickly increased temperatures. As ocean levels dropped, so did pressure on methane hydrates, causing them to be released into the atmosphere. Waters also warmed at the beginning of interglacial periods, further favoring release of methane. (f ) CFCs: inert compounds used at aerosol propellants up to 1978 in U.S. Tremendously more potent than CO2 . (g) N2 O 5%. Fertilizer application and fossil fuels. Long residence time in atmosphere. 5.
Forcing is any process that changes global temperatures.
6. Hypothesized negative feedback: (a) Global warming increases algae, which consume CO2 . (b) Greater [CO2 ] stimulates forest growth, removing CO2 . (c) Polar regions receive more precipitation from warmer air carrying more moisture; deposited snow re ects heat. (d) Warmer temperature evaporates more water from oceans, forming more clouds, which re ect heat. 7. Hypothesized positive feedback:
ing.
(a) Increase oceanic evaporation increases water vapor
55
increase warm-
(b) Melting of permafrost releases methane. (c) Reducing
summer snowpack
reduces re ection.
(d) People use additional air conditioning, burning more fossil fuels. 8. Both negative and positive occur spontaneously, but evidence points to positive being favored. Role of water vapor is critical and not well understood. 9.
Global dimming is the reduction of solar radiation by re ection o par-
seeds for clouds
ticles and their interaction with water vapor. SO2 and volcanic aerosols oset some global greenhouse eect because they at as
. In
some areas pollutants oset 50% of expected warming due to greenhouse gases. 10. Potential consequences: (a)
Polar ampli cation is positive feedback of ice melting, thus re ecting less heat.
(b) Climate change could damage agricultural productivity because optimal climate is not longer paired with optimal soil.
less
i. Runo may be much faster because snow pack is reduced, leading to
runo for more downstream regions.
ii. Could increase occurrence or magnitude of violent storms be-
has
cause warmer ocean water puts more energy into storms. Past hurricanes show average magnitude rence has not).
increased (but occur-
thermal expansion of water, melting of glacial ice.
(c) Rising sea levelshalf the people on earth live near the coast! Caused by (1)
(2)
i. Already 12mm/yr. Estimated 4555
cm by 2100.
ii. Increase coastal erosion, loss of wetlands, saltwater intrusion. (d) Glaciers melt, but Antarctic ice cap grows.
Consistent with models.
(e) Changes in biosphere: evidence of many animals adapting. i. Some species cannot adapt quickly enough, particular plants, ii. Wild relatives of crops used for hybridization may die. iii.
↑
range of mosquitoes carrying
malaria, dengue fever.
iv. Possibly responsible for spread of West Nile Virus to New York City. 11. Simply learning to live with global warming may not be the best idea because the rapid rise may bring many nasty surprises.
◦
If reduced to
below 2.0 C over the next century, then very likely to be able to adapt. 12. Reducing climate change:
56
(a) California (itself 12th largest greenhouse gasser) passed legislation to reduce emissions by 25% by 2020. (b) Conserve; use nuclear and renewables; use natural gas instead of other fuels. (c) Minimize burning of forests;
reforest.
(d) Geologic sequestration: capture CO2 and inject into reservoirs. Depleted oil elds or saltwater aquifer. Need to sequester 2 GtC/yr to be eective. i. Norway sequester CO2 from natural gas production facility under natural gas eld in North Sea. Expensive, but so is paying carbon tax. 13. Laws and Treaties (a) 1987
Montreal Protocol signed by 24 states to reduce and eliminate
CFC use and develop alternatives. Nearly phased out by 2000.
7.3
Loss of Biodiversity
7.3.1 Habitat loss; overuse; pollution; introduced species; endangered and extinct species
introduced to dierent biotic provinces (regardless of biome) likely to cause trouble
1. Species
because the introduced and local species have not evolved
with each other. (a) (b)
Ubiquitous species can be found anywhere. Cosmopolitan species can be found almost anywhere within suitable conditions.
(c) (d)
Endemic species can be found naturally in only one place. Exotic species are species introduced into an area where it has not evolved.
ened Species
2. International Union for the Conservation of Nature's
Red List of Threat-
(a) 20% known species of mammals, 12% birds, 4% reptiles, 31% amphibian, 3% sh, 3% vascular plants. 3.
Endangered species means any species which is in danger of extinction throughout all or a signi cant portion of its range [except insect pests].
4.
Threatened species
means any species which is likely to become an
endangered species within the foreseeable future throughout all or a signi cant portion of its range.
57
5. Causes of Extinction (a) Population risk: random variations in birth and death rates result in many individuals unable to nd mates. (b) Environmental risk:
non-catastrophic changes kill species.
Some-
times can be very isolated, for example, speci c pollinator/ ower relationship: if plants die, so do pollinators. (c) Natural catastrophe. (d) Genetic risk:
not
(
including environmental damage) genetic drift,
widespread mutation.
7.3.2 Maintenance Through Conservation 1. Goals: two approaches: (a) To some pretechnological number. Complex, inaccurate. (b) Seek some determinable number: minimum viable, optimal population, etc. i.
Minimal viable population is smallest
estimated population
to maintain itself and its genetic variability inde nitely. ii.
Optimum sustainable population
is the
largest
estimated
population to sustain itself without detriment to ecosystem. 2. Sometimes protection works too well:
sea lions, mountain lions
have be-
come problems for human life and property.
3. Spatial relationshipslooking at each specie's habitatcan allow for preservation of certain species without compromising other species.
7.3.3 Laws and Treaties 1. Endangered Species (a) 1973
U.S. Endangered Species Act listed endangered, threatened
species and was the most wide-ranging piece of environmental legislation in the 1970s. As of 2007, 41 species have been de-listed
58
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